How bad is your crash?
Is your hard drive still working?
What make and model is your laptop?
Does it have a recovery partition ?
Do you have a Vista CD/DVD?
Are you able to go into safe mode?
To go into safe mode boot up your laptop and tap F8 key while it is booting. You will then get a screen of options. You could try returning to last known working configuration.
If you tell us more about your problem we may just be able to help you.
☺ When everything else fails, read the instructions.