Are you getting a license not valid error, or something like that? If you could post more details including the exact message, that would help.
When your hard drive crashed, did you replace the drive or operating system - or make any other significant hardware/software changes to the computer?
Finally, what type of computer do you have, and which version of Lightroom?
That will allow us to help you better - thanks!
Here's more information! So it says that the licensing number is invalid. I replaced the entire drive and operating system--so it's basically like a new computer. I have a Macbook Pro and the register Adobe Lightroom I bought was 5.0. Is there any other information that you could use?
Ah, OK. So what's happened is Lightroom sees and believes it is a new computer, and obviously since your disk crashed you couldn't first deactivate the Lightroom license on your previous setup...
In which case, your only option is to contact Adobe directly and ask them to reset your license activations... (via live online chat is usually fastest/easiest) Have your purchase information ready when you do.
Hope that helps!
Okay, thank you!
There is no activation mechanism in Lightroom 5 (or earlier) so there's nothing to deactivate.
Activation was first introduced in Lightroom 6.