Macintosh HD disappeared from finder after "disk damaged and cannot be repaired" I have a MacPro 13.3 Inch mid2011 with 500GB storage and recently while performing a Mac update, it froze and was still stuck on a grey screen even after multiple restart attempts. I finally tried Command+R to attempt Time Machine(none were available), Disk Utility but "Repair Disk" was greyed out, and finally tried to reinstall Mac OS X but when it was close to completion, again, it showed Macintosh HD is damaged. 

I bought an external hard drive hoping to save my school work from Macintosh HD. 


Disk Utility>External Hard Drive>Partition>GUID Partition>Mac OS
Extended 
Ran OS X Installer and selected my External Hard Drive as the target. Near completion, it gave me the option of transferring my
information from another drive. I selected the first option (Mac
etc), but when it came to loading my internal drive, it didn't load.
I let it run for several hours but still to no avail so I skipped the
process and finished registering. 
When my Mac loaded, it showed the message that Macintosh HD is damaged. Please back up your files immediately. 
I loaded Finder, but Macintosh HD is not listed under devices. 
I loaded Disk Utility and at first it showed my Macintosh HD with my 69GB/500GB...but then it disappeared after I clicked on Verify
Disk. 
If I unplug my External Hard Drive, Mac shows a grey screen with a folder and question mark.


Is there anyway of recovering the data on my Macintosh HD now? 

If I don't replace the hard drive and just continue to operate using my external hard drive will that work? I am not sure whether it's better to just get a Thinkpad or repair/replace the internal hard drive. 

I appreciate all help and advice you can offer! Thank you
I wouldn't suggest continuing to use an external drive for your MBP, apart from anything else it's just not practical.  

It seems like your internal drive has or is just about to fail.  Have you/can you check it's SMART status from disk utility?  Either way, I would suggest not worrying about trying to verify or repair it - just try and get your important files copied over to your external HD/other back up disk whilst you can still get some access to it.

Replacing a HD in a MBP is actually quite easy, ifixit: https://www.ifixit.com/Device/MacBook_Pro_13%22_Unibody_Early_2011 has good instructions.  

I have replaced a HDD in a MBP 2012 and would rate it as moderately easy.  Hdd are fairly inexpensive these days and tools to do the job properly are available readily from Amazon for only a few quid.