The handle is broke to the shut off valve under my sink and I am wondering if I can just unscrew the screw going through it and put a new handle on then replace the screw. Can I do this with out having to replace the entire valve? There are no other issues ouside of the handle being bent.

Yes handles can be replaced very easily. There are several types so take the broken one to the store so you can match the spindle.

Can I do this with out having to replace the entire valve? I think Bob's talking about the handle on your sinks faucet. I think you're having an problem with the angle stop,(see image) in the cabinet. Since angle stops are so inexpensive simply purchase a new one and use that handle for your replacement. Good luck, Tom

Nope, actually talking about the stop under the sink. They are cheap, $4.00 but a handle is even cheaper and less labor.

there are several types how many types of handles do angle stops have? (You're never too old to learn). Tom

I lost count on this page Stop Valves by Kohler and Kingston Brass at PlumberSurplus.com (http://www.plumbersurplus.com/Cat/Stop-Valves/992/List)

Thanks Bob!
Like I said," Never too old to learn".