Used WD-40 on headset and now it loosens daily I've used WD-40 on my bike's headset as it produced some cracking noises. The result is a headset that gets loose after every ride.

I've tried to use a wrench to tighten it, alas, it went loose after a couple of days.

Any recommendation of how I can fix my mistake?

UPDATE - image of the bike.  It has a threadded headset and quill stem.
Using WD40 on a headset should not cause it to loosen.  Something else is wrong.  You need to find out what that is.

First - don't ride the bicycle until the problem is identified and fixed.  Doing so might be dangerous - both to you and anyone near, as you may lose control.

If your bicycle has a new-style "threadless" headset, the stem bolts may be undertorqued.  Or, they may have been overtorqued in the past and crushed the steer tube that the stem clamps on to so that it no longer stays tight.  Those are by far the two most likely problems with a headset that won't stay tight.

Park Tool has a series of good videos on bicycle maintenance.  This one is for troubleshooting a headset:


                
            

What you do to fix the problem depends on what the problem is.

Update:

Given the posted photo, this video appears more relevant: