|Did you REMOVE the main battery as well as unplug the AC adapter from the laptop while you were fiddling with the ram ?|
If you didn't, you may have damaged the ram modules or the ram slot circuits or both.
If you did, try re-seating the original ram again.
If you installed any of the ram modules backwards in a ram slot and then tried booting the computer, the backwards ram module and the ram slot circuits of the ram slot the backwards module was installed in were both fried instantly and neither can ever be used again.You would probably have noticed a strong smell like the smell of burning plastic.
The new ram modules may not have been compatible with installing them in your model.
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. SDram, DDR, DDR2, etc.; PCxxxx, xxx mhz) for your mboard. In the worst cases of incompatibilty your mboard WILL NOT BOOT all the way with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard's main chipset, or in the case of recent mboards, compatible with the memory controller built into the cpu.
If you still have the ram that was installed when the system worked fine, try installing just that ram.
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:
Once you know which module ID strings (part numbers) work in your mboard, you can get them from anywhere you like that has ram with those ID strings.
If you have brand name ram, it is usually easy to look up whether it's ID string (part number) is in a list of compatible modules found by using your mboard or brand name system model number.
If the ram is generic, that may be difficult or impossible.