hello michael but how can i know what i were doing?
Presumably you were sitting in front of your pc with Vegas Pro open. You must have some idea what you were trying to do. Import media, trim clips, add FX, render etc, etc........
Check "show problem detail", and if there show a dll causing problem, then rename that dll or delete it. This will resolve quite a few crash but not all.
You seem to be quite reluctant to provide any substantial information about the problem. Please refer to the first response from michael-harrison and follow the link provided so that you can get some solid information posted here about your set of circumstances.
This is really no different to when somebody has a problem with their TV or car - the service centre is going to want to know details about the problem so that they can go about fixing it. For example, things are not going to go well if a person takes their car to a garage to fix a problem but just say, "there's a problem with my car" and then walk away to leave the garage to work it out for themselves (which they almost certainly won't do).
Please read the previous comments above where help has been offered on the forum but you are not forthcoming with any real information for anyone to have the faintest idea of how to help you. It should be abundantly obvious that you are not helping yourself by not helping us.