How to gunzip files present in multiple subdirectories in subdirectories

I am learning Linux and I was trying the gzip command. I tried it on a folder which has a hierarchy like

Personal/Folder1/file1.amr
Personal/Folder2/file2.amr
Personal/Folder3/file3.amr
Personal/Folder4/file4.amr

I ran "gzip -r Personal" and now its like

Personal/Folder1/file1.amr.gz
Personal/Folder2/file2.amr.gz
Personal/Folder3/file3.amr.gz
Personal/Folder4/file4.amr.gz

How do I go back?