I got my iPhone disabled mistakenly by six trials of entering pass code. However now I remembered my passcode so how can fix the problem without losing my contents.

if it's permanently locked, there's no solution, unless you've created a backup.

Check out http://support.apple.com/kb/HT4113

and http://support.apple.com/kb/HT1212

If your phone is now disabled, you've already lost all data on the phone...that's the whole point of the passcode, to protect the data on the phone. Your only choice now is to force the phone into recovery mode & restore it, as described here:

http://support.apple.com/kb/ht1212

This will remove the passcode, but also erase all data on the phone unless you have a backup to restore from.