How do i know my compaq model?

If it's compaq and it's only a couple of years old it's an HP. If it's a laptop when you open the lid it should have the make and model number up by the hinge. If not it should have a service tag number or serial number on the bottom and you/us can look it up from that. If it's a desktop there should also be a label somewhere on it that gives you those coupla of numbers also. If you can see it's a compaq there should be some numbers next to that as well and that's usually the model number.

Look at the case, unless all of the stickers are off it, you will find a model number listed there. May have to check the back.