It is never a good idea to open a laptop case that is still under warranty. No matter your level of experience or expertise, leave it to the professionals if the warranty is still good. Opening a laptop automatically ends the warranty and rather than having some of the costs covered, you will be on your own.
Most laptop parts are not interchangeable (with the exception of memory and hard drives). An excellent source for finding correct part numbers is www.sparepartswarehouse.com. By entering the vendor/model line, choosing laptop series and model, you can find the part you need. Then search for teh part by number on ebay or Google to find an inexpensive replacement.
For a laptop that has been dropped, first reseat the connectors inside. Then try reseating the memory module, and the wireless card, then the CPU. Do these steps in this order until one of them solves the problem. As a last resort, if none of these steps work, then disassemble the laptop and start assembling it back from scratch.
