When I turn my computor on, it doesn't boot up properly!

This problem just occured this morning, go easy on me as I dont understand any of that monetor or system restore stuff.

I have a dell inspiron 15R and have nearly used up all my ram with only 88GB left, I use my laptop for youtube so i have a lot of big files. I use my computor mostly for video editing i encountered this problem before amd after around 10 minutes the desktop came on.

I originally thought it was a loading issue so i was not bothered by it, but I booted my laptop up this morning and had the same black screen issue and this time I left it an hour but the desktop wouldn't come on.

Normaly when I turn it on, I see the dell startup thing or the breif command prompt screen, then the starting windows screen apears and then it asks for the password and then it loads and everything is fine.

This morning however when i turned it on the Dell startup screen and the command prompt didnt apear, instead it just showed the starting windows screen and then as soon as i logged in all I could see was a black screen and the mouse, I left it avout an hour but nothing happened. I closed the lid and opened it again which took me back to the windows 7 login but as soon as i logged in it just took me back to the black screen again with only the mouse displaying.

I doesnt say "Welcome" when i sign in either it just takes me to a black screen where all I can see is the mouse and nothing else.

This is really iritating for me as I was in the middle of editing some of my finest videos ever created that I spent two days working on.

I dont understand what windows recovery is or any of that hardware stuff, it just seems to tedious and long winded.

Do you know any way of getting it so that it boots up properly and everything, so its back to normel?