can data be recovered from a crashed hard drive?

Only by a service such as DriveSavers.

(142445)

It depends on what you mean by "crashed."

If you mean the disk, or the computer, was physically bumped or dropped and the spinning hard drive and the read/write heads made physical contact then that drive made not be recoverable, at least not without going to great expanse using a drive recovery service.

If you mean that the software crashed and wrote bad data to the hard drive then you may be able to recover it using Disk Utility, or something better like Disk Warrior.

http://www.alsoft.com/DiskWarrior/

If you are having difficulty starting up the computer try starting it up in Recovery Mode. From there you can run Disk Utility to try and recover your data.

OS X: About OS X Recovery - Apple Support

Possibly. But the more you mess with it the less chance you have of recovering anything.

1. If you have another Mac available try starting the failed one in Firewire Target Disk Mode and copying the data off that way How to use and troubleshoot FireWire target disk mode - Apple Support

2. Try data recovery software like Data Rescue 4 https://www.prosofteng.com/datarescue-mac-data-recovery/

3. If your data is really valuable contract with a professional data recovery service like DriveSavers http://www.drivesaversdatarecovery.com/