I didn't notice that my opponent forgot to press the clock and made my move. What should I do? My opponent made a move but didn't press the clock. I didn't notice, so I made my move and then realised that the clock is already pressed. Am I allowed, under FIDE rules, to press the clock two times: first for my opponent and then for me?
According to the FIDE Laws of Chess:

6.2.2 A player must be allowed to stop his clock after making his move, even after the opponent has made his next move.

and

7.5.3 If the player presses the clock without making a move, it shall be considered and penalized as if an illegal move.

Together these mean that you would be wise to press your opponent's clock, press your clock and then tell your opponent that you have done so.
If you don't do so then 6.2.2 means that your opponent is entitled, after you move, to press the clock to complete their previous move. If you are not at the board then your clock can run while your opponent thinks.
7.5.3 means that you should tell your opponent so that they are aware and do not &quot;remember&quot; they forgot to press the clock and press it without making a move.