Power is not switching on

does it turn on with the ac adapter connected.......

does it turn on with the battery and the ac adapter disconnected?

Remove the battery and unplug the system.  Hold the power button for 30 seconds.

Remove and reinstall both memory modules.

Verify that the LED on the AC adapter or cord is ON before you plug in the notebook end.  If it's not, the adapter is bad;  replace it with a new OEM Dell adapter.

If the adapter is OK, plug it in and try powering up.  If the system will power up on AC only - no batttery - the battery is bad - replace it.

If the system will still not power up, the mainboard is bad - replace that.

Even if I connected without Batary - Means direct AC adapter, ITS NOT WORKING.

Please suggest what to do!

No, there's no "protection circuit" - if the board won't power up, it may or may not be repairable but it'll probably cost more to have it evaluated for repair than it will to replace the board.

Can I sell the laptop to DELL ? is it possible?

Because contacted Customer care, the cost of Motherboard is almost half of new laptop...

Sell, no - if you want to sell the system for parts, you're on your own.

I think its Motherboard problem...  I tried reinstalling RAM(memory) as well Hard disc .. not working.

There should be something some circuit to protect Motherboard right? May be that is wrong?

Is there any possibility to replace only that part of Motherboard?