My phone has a phone lock and I don't know the key.

The strange thing is, though, I don't remember making a phone key. I turned off my phone after school, and when I turned it back on it had a phone key. I have a certain four number pin that I usually use, and it doesn't work! Any way to bypass the lock or unlock it?? If not, if I return the phone to the shop, will they remove the phone lock?
YAY!! I found the solution myself. It was 0000.

Whoever posts an answer first will be voted best answer!!!