for ps3 the default is 0000 if you go into settings and restore the ps3 to default it will reset it to that
if its PS2 go the link below:
for the wii go here:
and for xbox do this:
If you've forgotten your pass code, you can reset it by answering the pass code question you set up parental controls. Here's how:
1. On your console, go to Settings
, and then select Family
2. Select a content control setting to change.
3. When you're prompted, enter any pass code (even though it's incorrect).
4. When you're notified that your pass code is incorrect, select Reset Pass Code
5. When your pass code question appears, use your controller or chat pad to enter the answer, then select Done
If you can't remember the answer to your pass code question, you'll have to contact Xbox Support
for further help.
...............hope that helps