i have an acer aspire. i try to open press the power button but only 5 to 6 seconds starting sound then it will shut down and will try to open again by itself then shut down again not even seeing opening on the monitor.

Could be memory failure. If you have two memory modules installed, try removing them one by one. Test your laptop with each module separately.
If you have exactly same problem with a known good memory modules and the laptop keep restarting on its own, probably this is motherboard failure.

i have a sony vaio pcg-7a2l. it will power on . the three lights that tell you that the numberlock and caps on light up and stay on.it never moves from this postion. neither logo or boot screen. the power led light is on , hard drive lights comes on and goes out. wifi light is on. nothing else happens.

First of all, I would check memory modules. Maybe one of the memory modules is bad and the laptop will not start because of that.
Do you have two memory modules installed? Try removing them one by one. Test the laptop with each module separately. It’s unlikely that both modules are bad.
If one of the modules is bad, the laptop should start properly with the second one installed.

I have a toshiba satellite a305-s6872 and I bought a new battery and done a bios update but it won’t charge my new battery had a guy who has the same battery pack and charger try it in his and the battery started charging and my power adapter charged it to he said he thought it was the charging circuit how can I tell if its that or something else?

It’s not very clear. Did you test his battery pack and adapter with your laptop or you tested your new battery in his laptop?

I have a DV2000 that wont turn on too save my life,the AC is good, and the battery is w.e but even if the battery sucked the computer is suppose to show that electricity is going threw, because the light on the side lights up, but there is no power. I opened it up and everything seemed to be okay, I really dont know what to do anymore.

Most likely this is motherboard failure. This is a known issue with HP Pavilion dv2000/dv6000/dv9000 laptops: http://www.insidemylaptop.com/free-repair-hp-pavilion-compaq-presario-laptops-out-of-warranty/

Rain fell on my laptop (dell,inspiron 1501) through window.when i on the computer,it shows light and off since then.i dried it on the sun,yet nothing happens.this is 4months now.what should i do?

I cannot tell what is wrong without looking at the laptop. It’s necessary to disassemble the laptop and take a look at the damaged. Probably the motherboard was damaged by the rain.