You can undo your local changes at any point in time before a check-in.
To undo your local changes:
The selected files will be restored to their pre-check-out state.
Uncheck-out works on:
Since the Uncheck-out operation involves only your local copy of the project, no scripts are propagated to other project members. The Un-CheckOut updates the timestamps on relevant files. This is done in order to force the rebuild of the project in your development environment. However, if there were no changes to a file, the timestamp won't be changed.
See also: