|The screen symptoms you described sound like a possible problem with the graphics card; presuming that the screen itself is OK (screen hasn't been physically damaged).|
Hard to determine from what you describe... but what happens when you boot up though. Does it boot into a desktop?
Regardless - you might download and burn to a DVD the (free) ISO for ubuntu (ubuntu.com). Boot with that DVD. It will load itself into RAM only. Presuming it does load OK you can then (hopefully) access the hard drive and copy your files various to external storage (DVD and/or an external hard drive). Wise to regularly copy/duplicate personal files (whatever they may be) to external storage. That way if the system does go wrong your personal stuff is safe elsewhere?
It will also in effect checkout the hardware of the system too if it loads and displays the desktop OK.