It wont start. Buying a starter but was told it might be the "cylnoid"?

Buying a solenoid without a starter is the same as buying a hamburger without the bun. The solenoid sits on top of the starter in a GM and they come out and go in as a pair. If you go in to buy a new starter it should have a new solenoid already on it. Replacing one without the other pretty much guarantees that you will be doing this job again a few months down the road for the part you didn't do this time. Hope this helps.