i forgot my administrator name and password so that i cant open the system preferences

If you have forgotten the admin password completely but you have iCloud verification code, all details of Apple ID , iCloud ID , webmail ID and respective passwords , base station or wireless network password for air port utility in records .

Shut down the system through apple logo , press command , R and power key simultaneously , release the keys when apple logo appears , the bar starts loading let it be completed , select the language as English .

Take cursor on top menu bar > click on utilities > click on terminal in the terminal window execute a command resetpassword and click on enter key .

A window appears , select your admin name , enter the password for Apple ID .

Two options will be shown ( a ) previous ( b) next , click on next

Select your user account , you have to press forcefully on the trackpad to get it selected .

Some fields will appear .

New password ……

Verify password ……

Hint ……

Fill up the credentials ( enter a new password ) and click on next then you have to click on restart .

The Mac will restart but you will see pop ups as this Mac can’t connect to iCloud because a problem with your mail address open iCloud preferences for problem.

You will see two options ( a ) Later ( b) iCloud preferences

And on the top right corner web mail ( could be gmail ) pop up will be there stating google password required enter your password for gmail address and showing close and continue .

Open system preferences > click on iCloud you will see the box for keychain is unchecked, so check mark the box a small pop - up will come on the screen after a while to enter iCloud verification code so enter it .

Make sure your trusted mobile is opened , after a while six digit code will come through sms on the mobile .Enter the six digit code on the next pop up .

You will see iCloud Keychain is setting up and a small circle is rotating the box for keychain is configured with iCloud server .

Now , on the top right corner of the desktop a google pop up is showing , click on continue a window will appear enter your gmail password so that is also configured .

Open airport utility through spotlight , click on base station you will see that password is empty , click on edit a pop up window will appear enter the base station or wireless network password .

Keep the box checked for remember this password in my keychain .

The settings will go to default .

Open safari and you have to reset the homepage once again ( open safari preferences click on General , enter the search engine link and take cursor on history > click on home and close safari window , a pop up window will appear change home page , click on it ) .

Lastly shut down the system when login window appears you can enter admin name and " new password " in the fields .

Note : If you enter in user library ( click on finder Go > hold option key and click on library ) > Find a folder keychains you will see login keychain is renamed and its a confirmation that login password has been changed and always be careful once login password is changed don’t delete login_rename …Keychain-db or previous login.Keychain-db from user library > keychain folder , if it is deleted the keychain application will be corrupted .

please tell me to reset the administrator name and password.

dominic23 already explained how to do that.

There isn't one "Administrator" account on a unix machine. You can create as many as you'd like.

If you are unable to use the one you have, then you can create a new one as shown in the link I provided.

Here are some suggestions from Apple: Change or reset the password of a macOS user account - Apple Support

Reset Password

Reset Administrator / UserLogin Password

macOS Sierra 10.12 and macOS High Sierra 10.13

Shutdown the computer.

Start the computer, then press and hold down command and R keys to start into recovery partition.

When you see the Apple logo and the progress bar, release the keys.

You have to press hard the Trackpad to register the click.

Select the “Language”, if not already.

Click the arrow button at the bottom.

Wait until OS X Utilities window shows up.

Move the mouse pointer to the menubar at the very top of the screen, click "Utilities” and then select "Terminal"

from the dropdown.

Terminal window will appear.

Type in resetpassword and press enter on the keyboard.

Reset Password window will open showing all user names. Write it down.

Quit Terminal.

Select a user to reset the password for.

Click the “Next” button at the bottom.

Enter a new password, enter it again to verify, enter a hint and write down the password entered.

Click the “Next” button at the bottom.

Password reset confirmation message will appear.

Click the “Restart” button at the bottom.

Log in.

When Keychain dialog box appears, select “Create New Keychain”.

Section: Create New Keychain https://support.apple.com/en-us/HT202860

For other methods: https://support.apple.com/en-in/HT202860

In Users & Groups system preferences, does it show "Admin" in the name of that user?

If not, you'll need to create a new admin user.

https://www.macissues.com/2014/08/12/quickly-re-create-a-missing-admin-account-o n-your-mac/

I can't unlock the settings.

We understand that. You must follow the directions that dominic23 posted and if that doesn't work, follow the instructions in the link I provided to create a new admin account. You can then use that to reset the password on your other admin account.

If you have tried out suggestions, then please tell us what happened when you tried them.

We have provided all of the help you need to fix your problem.