|I forgot to warn you to unplug the power and remove the laptop battery BEFORE doing that.|
Snapping the RAM in and out will not affect your files.
The POST screens are the messages you see before Windows starts. You should see maybe a brand name and a model number along with CD or similar.
The idea is to make sure the drive is configured by the BIOS before Windows even starts. If that doesn't happen then it is impossible for Windows to make it work. So that helps us identify where the problem lies.