OS is not booting up

Hello, I have MacBook Pro mid. 2009 and its not booting. My mb was in a sleep mode, when I open'd up it asked me to type in password but I could not do that because instead of a mouse it showed me spinning mouse logo so I turn it off with power button. When I turn it on it just showed me apple logo and spinning bar. At first I thought it was OS problem so i decided to reinstall, but it kept showing that he cant unmount the HDD and disk utility finds the HDD but as well it is not allows me to do any changes. The HDD is is working I all ready tried it on other laptop.

You can't make changes to the hard drive as long as it's mounted. It has to be dismounted first. Boot the machine with your install DVD and use Disk Utility from the disk to check the drive and make repairs if necessary.

The thing is that he dosent want to unmount the hhd. I tried to make repairs as well, it didint worked.

If the hard drive can not be dismounted, you have to remove it from the machine, place it in a carrier and make repairs that way if possible. The hard drive might be defective even though you say you tried it in another machine.

What are you trying to do with you're hd ?
Do you have a install DVD of Snow Leopard ?
If so boot from the dvd than you're Hd is not mounted .
And you can make chances using the diskutil

I had external hard drive so i used its carrier, the hard drive worked fine, but when I placed back in laptop nothing changed anyway he tried to unmount. As well I had tried puting in my externals hard drive in laptop but he acted the same as with original hard drive.

Maybe I should had mentioned that I had upgraded my rams from 2GB to 4 GB. I changed them back and tried the same: changing hard drives, installing different OS. Even I had OS in flash drive, tried to install it from it. Nothing.

It seems I had tried everything what I could, but nothing helped. Maybe its motherboard...

To dobby.
After system failure I tried to install OS, I thought it should help. But laptop says it failed to install or tries to unmount the hard drive.
I have Leopard, Snow Leopard, Tiger. Non of them helped .

If you are trying gray Install/restore DVDs from other Macs, they can't work because they don't have the correct drivers available.
You have to use the correct DVD Or, a retail DVD newer than the release date of the computer.

I suppose that English isn't your first language - I'm sorry we're having trouble understanding what you want to do.

We don't understand what you mean when you say "he doesn't want to unmount the hhd (hdd)."
Unmounting doesn't mean physically removing the drive from the computer - it means logically not accessing the drive, which allows Disk Utility (or installer) to have complete control to do repairs.