My iphone is showing iphone unavailable. i am not able to connect it to a device nor i can reset it please help!

If you forgot your passcode, you can use your Apple ID and password to erase and reset your device without a computer.

If you enter the wrong passcode on your iPhone Lock Screen too many times, an alert lets you know that your iPhone is disabled. (Learn what to do if you see "[Device] unavailable" or "Security Lockout" on your iPhone or iPad.)

Connect iPhone to Computer / Mac

Settings > Touch/Face ID & Passcode > USB Accessories > [Enable]

You haven't mentioned whether you have a PC or Mac. However...

1. Use your USB lightening cable --> Resolve USB-related alerts in iTunes - Apple Support
2. If unable to connect --> If iTunes doesn't recognize your iPhone, iPad, or iPod - Apple Support
3. If your computer is a...
   1. Mac --> If your computer doesn't recognize your iPhone, iPad, or iPod ...
   2. Windows PC —> Troubleshooting issues with iTunes for Windows - Apple Community
4. Use genuine cable --> Identify counterfeit or uncertified Lightning connector accessories ...
5. See how to --> Sync your iPhone, iPad, or iPod using iTunes on your computer ...
6. To reset the passcode for disabled iPhone -> If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...
7. Learn how to--> Update your iPhone, iPad, or iPod touch - Apple Support

If you are experiencing an issue not listed here, contact support

The option to connect to an iPhone in the Finder can disappear due to various reasons which can be easily corrected...

1. Check your iPhone connection: Make sure your iPhone is connected to your computer using a USB cable or Wi-Fi connection. If the connection is weak or unstable, it can prevent the Finder from detecting your iPhone.
   1. Use your USB lightening cable --> Resolve USB-related alerts in iTunes/Finder - Apple Support
   2. If unable to connect --> If iTunes/Finder doesn't recognize your iPhone, iPad, or iPod - Apple Support
   3. For your Mac --> If your computer doesn't recognize your iPhone, iPad, or iPod ...
   4. Use genuine cable --> Identify counterfeit or uncertified Lightning connector accessories ...
   5. See how to --> Sync your iPhone, iPad, or iPod using iTunes on your computer ...
   6. Here is the process to --> Backup on iTunes/Finder.
   7. If you are experiencing an issue not listed here, contact support
2. Restart your iPhone and Mac: Sometimes, restarting your devices can help resolve connection issues. Try restarting both your iPhone and Mac and see if the import option reappears.
3. Check Finder preferences: Open the Finder app on your Mac and click on "Finder" in the menu bar. Then click on "Preferences" and select the "Sidebar" tab. Make sure the "CDs, DVDs, and iOS Devices" option is checked. Please see the pic below
   1. 
4. Have you trusted the device: Please see the pci below
5. 
6. Update your software: Make sure both your iPhone and Mac are running the latest version of their respective operating systems. Outdated software can sometimes cause compatibility issues.