'Preview' not working

Hi guys,

New mac user here so apologies if this is obvious. Was copying lots of photos form an ext hard drive to my beautiful new mac the other day when it everything froze. I had to hard reboot and now Preview does not work. It asked me to relaunch and reset which I did and now nothing. Doesnt open or anything. REALLY need it as I have around 7000 photos to sort through.....help!

thank you

First off, it's rare that a UNIX-based OS completely locks up, unless there is a hardware problem. So, if you ever experience a situation like this, the first thing to try is to do a Command+Option+Esc. This should bring up the "Force Quit" window and allow you to rid yourself of the offending application.

But for those times that a forced shutdown is necessary (and they should be few and far between - again, unless there is a hardware issue), it's certainly possible that something in the filesystem was damaged. The first thing I would do is a Verify & Repair Permissions in Disk Utility (Applications => Utilities). Then, do a Verify and Repair Disk. If all else fails, you can start the machine in single user mode and run fsck, although this should only be used as a last resort.

Details here:

Resolve startup issues and perform disk maintenance with Disk Utility and fsck