I have forgotten my app lock password

Probably you mean Screen Time Lock password,

If you have forgotten your Screen Time passcode

Use this link to reset your passcode If you forgot your Screen Time passcode - Apple Support

If you are unable to reset Screen Time passcode from the this-> link then, you will need a computer. If you don't have one, borrow from a friend.

Forgot? Click below to reset…

Click->If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...

If you mean Lock Screen Passcode then note this below...

If you had attempted unlocking multiple times with incorrect Lock Screen passcode, or if a message says that your device is disabled, learn what you need, what you get and what is lost.

You need a computer to follow these steps. If you don't have a computer, borrow one from a friend.

Forgot? Click below to reset…

Click->If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...