I cant restore my phone through itunes and forgot the passcode. How do I restore it?

Follow the instructions in this Apple support article—>If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support. Follow them very carefully, to the letter, or it won’t work.

You will need access to a computer with iTunes.

If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled

The only other possibility would be to erase the device using Find My iPhone, assuming you had that set up and the device still has a data connection.

Then verify that you have the most recent version of iTunes (or at least version 12.8.2) on your computer, and even if you do reinstall it from https://Apple.com/itunes (unless your computer is a Mac running Mac OS Mojave, which has iTunes integrated into the OS). And if you have Catalina it will appear in Finder rather than iTunes.

If none of this helps see—>If your computer doesn't recognize your iPhone, iPad, or iPod - Apple Support