Laptop's dying -is it broken cpu or hard drive stops laptop

Hello,
i have big problem with Advent laptop,is basically dying on me , and am very worried,
any helpful info will be greatly appreciated.
It wont stay on ,for more than few mins, its power converter gets extremely hot in 5mins, and the surface underneath, is unbearably hot, after 5mins.
Its been overheating for months , i have to say i ignored it,
and kept using it with AC adaptor, always plugged in for hours,
as laptop's battery could only last 10 mins.nomore,.
and that has been the case for few months now.
The last two days it started swtiching off on its own , and staying on gradually less and less,
and now it will only turn on ,after i tried several times...
it may reach Windows or not...and then it just goes off ...very quickly...
I know not a thing of how to replace or change or even take the battery off it,
i just know that am in massive anxiety, please help me,
as i fear ive lost not just my laptop, but my files and data..
...what will hapen , have i lost it, or can it ever be transferred somewhere else and how?
..i will appreciate any piece of information,
whether it can be repaired or its worth bying a new one,coz of the cost of repairing it.
i havent got a warranty , as its 5 years i have it.
shouldi keep turning it on ,or leave it alone until i know what to do?
Thankx so much ,mariane

(i use Vista basic,
and its 6months now, that i have to switch laptop off manually , as it stays on the 'shutting down mode' interminently , so have to press off button to turn it down)

thank you

Well, technically you're not likely to lose your data even if the power converter on the motherboard is going out, as the hard drive should be left unaffected.

Have you tried taking the battery out? It's on the underside of the notebook, and very easy to remove.

What's the model number of this Advent laptop?