"Where can I buy a replacement battery?"に関する回答The replacement battery needed for the Samsung PL200 has model number BP70A. It can be purchased on Amazon for $10.50.
"Why will my camera not turn on?"に関する回答Check to make sure that the charger chord is completely unobstructed to ensure a good connection. It is also possible that your battery needs replacement. A guide to do so can be found here.
"My screen is scratched?"に関する回答Replacing the screen is actually fairly simple. You can follow this guide for step-by-step instructions on screen replacement. If the scratch is not very deep, you could first try patching it with Displex, Brasso or similar products.