Last night I updated some stuff on my macbook and left it while it updated now the screen stays grey when i turn it on and wont do anything, ive tried putting the software disc in and holding c and nothing happens?? why?? please help!!

I would first reset the SMC and pram and if that didn't fix it I would do a safe boot.

To reset the SMC

Shut down the computer.

Disconnect the MagSafe power adapter from the computer, if it's connected.

Remove the battery.

Press and hold the power button for 5 seconds.

Release the power button.

Reconnect the battery and MagSafe power adapter.

Press the power button to turn on the computer.

Resetting PRAM and NVRAM

Shut down the computer.

Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.

Turn on the computer.

Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.

Hold the keys down until the computer restarts and you hear the startup sound for the second time.

Release the keys and allow your Mac to restart.

Safe Boot - http://support.apple.com/kb/HT1564

Hopefully you have your original install discs or a retail set of OS X install discs. The next step would be to insert a disc and start up while holding the C key. After you select your language you'll get a screen with a menu bar, from there select Utilities/ Disk Utility and repair your hard drive.

This is the original disc that came with your computer correct? Insert the disc. Hold down the power button till the macbook shuts off completely, release the power button. Now that the mac is completely shut down press the power button again while holding the C key down, do not release the c key until the Apple shows up on the screen. The computer should continue to start from the optical drive, this will take much longer than a regular start up. Select your language, go to the Utilities menu and select Disk Utility. Repair your hard disk.

If the above steps don't work and you've properly reset your SMC and pram I don't know what else to suggest.

Monkeymick wrote:

I tried the install disc again and still nothing comes up on the screen?

Have you tried single-user mode? Turn on the power and press Cmd-S when you hear the startup tone. It should go to a black, text-mode screen. Assuming it boots to a command prompt, type 'fsck -fy' and then press Enter. If it manages to check the file system correctly and/ repair it, then you can type 'reboot' and then Enter when you're done.

If fsck returns errors, let us know what they are.

Thank you. I was just looking that up. I didn't remember if fsck was still valid with newer software.

Anyway....

Monkeymick, here's a link explaining what Trane is saying.

http://support.apple.com/kb/TS1417

Unless Trane ones up with something I'm out of advice. You've tried SMC an pram resets, safe boot, starting from install disc and finally single user mode, I'm sorry but I don't know what else to suggest except to take it in for service.

Try restarting your mac with the disc in the drive and hold down the shift key and click on the disc drive and you sbould be able to reinstal

Your software.

Correction hold the option button

Yeah, I'm with Mike on this. Time to take the wee beastie into Apple or an authorized repair shop and have it looked at. This is sounding more like a coincidental hardware failure than a software issue.