|"My hard drive is Western Digital, and I applied the long test and also I get nothing just saying "Fine" "|
In that case your hard drive is okay but the data on it may not be.
Did it mention there were problems with the data on the drive?
If it didn't, there are no serious data problems on the drive.
If it did.....
Your hard drive must boot every time in order for you to be able to try fixing the datqa on the drive.
If you can get it to reliably boot but can't figure out the data problems, you can get the Rescue or Recovery or similar CD set from the manufactuer for your model and re-load all the original software yourself - it often costs a lot less than even a OEM XP Home CD.
"...one thing I didn't check is the RAM Modules you are talking about, I just didn't deal with laptop hardware before so, is it risk to check the RAM myself ?"
No, as long as you don't do anything dumb.
E.g. See the last part of response 5 - you must remove the main battery and the AC adapter when you do that.
Also check your hard drive's connection as in response 2 if you haven't already tried that.
If you do a ram test, do that AFTER having tried cleaning the contacts and making sure the ram is seated properly - otherwise any errors found may be FALSE.
If the ram is incompatible with the chipset, it will likely FAIL a ram test - that is NOT a true indication of the ram being faulty - there is probably nothing wrong with it, and it will pass the test if installed in a mboard it is compatible with.
Ram that works in another mboard , or any ram you buy or have lying around, may not work properly, or sometimes, not at all - even if it physically fits and is the right overall type (e.g. DDR, DDR2, etc.; PCxxxx, xxx mhz) for your mboard. In the worst cases of incompatibilty your mboard WILL NOT BOOT with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard and it's chipset.
See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure:
Correction to that: