Password cracking guidance

[nohabloespanol]

Hello, 
I am having difficulty logging into a laptop running an Ubuntu operating system with full hard disk encryption. I know what the password should be but it may have been misspelled. If anyone could help point me in the right direction or give some guidance on how to proceed with cracking this password it would be much appreciated. Thanks!

[royce]

The magic word you're missing is "LUKS".

This should yield a few reasonable howtos:

https://www.google.com/search?q=LUKS+hashcat