So here you will see how to restore your original opera settings:
1- show your hidden files from (my computer - tools menu - choose folder options - from view tab - check "show hidden files and folders"
2- for windows 7 close opera then go to (C:\Users\user_name\AppData\Roaming\Opera\Opera\)
for windows xp close opera then go to (C:\Documents and Settings\user_name\Application Data\Opera\Opera)
3- locate and delete the file called "Operapref.ini"
4- open opera and this file will be rebuilt automatically
by that you restore your opera original state, thanks......