Can I restore my iPhone without using a computer and I forgot the passcode

You can try using these instructions from Apple. If not successful, you will need a Mac or PC to reset the phone. Chances are, you have a friend who has a laptop who would let you use the computer for 20-30 minutes. You can also take the phone to an Apple Store and use a Mac there.

How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

Your data is not lost if you have a backup either on iCloud or iTunes.

If you see an iPhone or iPad unavailable message or "Security Lockout" screen

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

Learn what to do if you see "[Device] unavailable" or "Security Lockout" on your iPhone or iPad.)

iPhone is disabled.

Following this process is the only way out if your iPhone is disabled. The steps given in this link will help you reset the passcode -> If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...