what is a word that means wishing you would have done something diffrent?

desiderate

hankering

yearning

brood

mull over

As was suggested earlier, the most common would be regret, or remorse.

“Regret carries no explicit admission that one is responsible for an incident, while remorse implies a sense of guilty responsibility and a greater feeling of personal pain and anguish ”

You could also go with something like dissatisfaction, dissappointment, repentance or attrition (although the last two are more commonly associated with the attonement stage, they both mean remorse.)

“regret carries no explicit admission that one is responsible for an incident, while remorse implies a sense of guilty responsibility and a greater feeling of personal pain and anguish.”

copied and pasted from the source below.

Edit:

Dang… too slow… Great minds and all that…

regret

regret

remorse or regret, maybe

remorse, rue