Led lights on yet nothing on the screen

You mentioned that it won't turn on with the charger (without the battery). Does this mean that it turns on if the battery is in?

If it turns on with the battery, then you need to replace your AC adapter.

If your laptop appears to boot up and the hard disk LEDflashes, then the problem is probably a back light fault. This can be a faultyinverter or a faulty CCFL lamp. Please click on this link and follow myinstructions to identify the fault and possible fix :- http://www.fixya.com/support/r3598095-faulty_laptop_lcd_screen

sounds like your screen inverter has stopped working.

Sounds like a vedio card problem!

You're probably one of thousands of victims of defective nvidia chipsets in these systems. Call HP and complain.

remove again the hdd then insert again....

Sounds like a back light problem

Try this:
I left mine on, in its coma cond overnight. The next am I touched the enter key and it booted up! 5 days later it went back into is coma.
Yeah, Toshiba Laptops ****! My A135 S2246 is doing the same thing. You and I aren't alone either. Search for: "toshiba sucks" and you'll see how many there are, lots of them. 1 week after warranty expires it started doing exactly what yours is doing. I swapped out ram with known good ones, HDD also, I connected external monitor, keyboard, nothing changed. I re-seated the CPU, temp disconn cmos batt -no help.
Cleaned all the connectors & grounds, no help.
Observations:
Fan runs on & off, I feel heat being pushed out.
Can hear Hdd spinning, indicator led briefly flashes when I first turn on.
Fn indicator led will illuminate, sometimes.
caps lock led -not at all.
numeric keypad led, no.
the only key that seems to do anything is Fn.
Toshiba wanted $35. just to discuss it over the phone. -WRONG!

Its now two years old and about as useful as a milk bucket under a bull!

are the drivers corect?

Definitely try without the battery. These models are known to have a "short" problem, usually with the palm rest, which causes this failure, although it usually is more sporatic, and doesn't happen 100% of the time.
Also, can you remove all but 1 piece of memory.
Good luck, and let us know what happens.