About 6 months ago, my computer blue screened after crashing on a system configuration and me having to turn it off after being frozen for 18 hours. I went through hassle for about 2 weeks and eventually got it working (forgot how). Ever since then, my computer has been terribly slow, fps awful and struggles to even run youtube videos without freezing for a second every 5 seconds (audio carries on). On top of this I am not allowed access to any major changing software on the computer, eg. almost all control panel options, system restore and other major files. I do not have the disk to recover the laptop that way. My laptop is a Dell inspiron n51100. Another recent issue, is java has just stopped working, within in last 2 days, which is another pain, I've tried reinstalling but no help.
Any help is appreciated.