How can I run a hardware test on my Macbook pro mid 2010

http://support.apple.com/kb/ht1509

If it came with an isntall disk, put it in the drive and restart, holding down the D key.

If it didn't come with a disk (Lion pre-installed), just hold down the D key when you restart.

http://support.apple.com/kb/PH11342

If your system is new enough, then you can hold Option-Command-D to load the Internet Recovery mode, where it will download the tools from Apple's servers and run them that way, instead of requiring they be on the local drive somewhere. This option does require an accessible and working Internet connection.

And if you're connecting to the Internet using wifi to run Internet Recovery Mode, Apple says the wifi router's login password protection has to be set for WPA/WPA2 Personal, rather than Enterprise (and especially rather than WEP), though I don't know if it will work when set to WPA2-PSK.

However, many people (including myself) find that their Macbook Pro 15 Inch Mid 2010 can't do Internet Recovery Mode, even though Apple says it can, no matter what you do; maybe it works with some of the Mid 2010 Macbooks, maybe the ones that were produced during the later production runs. MacBook Pro EFI Firmware Update 2.6 will get some of them to do Internet Recovery (use the App Store app--if the firmware update doesn't appear under the Updates tab, the Macbook's firmware has already been updated), but for some even this doesn't help.

Here's a link to Apple's article on this:

Computers that can be upgraded to use OS X Internet Recovery - Apple Support