You can use the following command if you do not know the exact path:
$ git log --all --full-history -- **/thefile.*
Use the following command If you know the path the file was at:
$ git log --all --full-history -- <path-to-file>
This command should display a list of commits in all branches which touched that file. Now you can find the version of the file you want, and display it with...
$ git show <SHA> -- <path-to-file>
Or restore it into your working copy with:
$ git checkout <SHA>^ -- <path-to-file>
The caret symbol (^), which gets the checkout prior to the one identified, because at the moment of <SHA> commit the file is deleted, we need to look at the previous commit to get the deleted file's contents