Assuming you do not have a local copy, you can either open it from Vault, or Get latest version. You can check it out from IV or from Vault Explorer (VE).
When you open the file it will only ask you if you want to check it out if there are changes.
NOTE if you have made changes to you local copy with out it checked out (a green circle is shown next to a file). If you perform a Get latest it will overwrite this file and you will loose the changes. This can be a benefit if you saved changes you didn't want.
Pete