We have FAQ articles posted in our Support Portal, however Harmonix doesn’t handle repairs, warranty replacements, nor do we sell hardware or replacements.
If you are within warranty, you should contact the manufacturer of your instruments. This is either:
Electronic Arts (Rock Band 1, Rock Band 2, The Beatles Rock Band)
Mad Catz (Rock Band 3)
OR, if you are needing help with the Fender Squier PRO Guitar
If you need to buy new gear, check out online retailers such as MadCatz.com, Amazon.com, eBay, Best Buy, Gamestop, etc.