Finding changes for table-valued function definition on SQL Server
The answer is unfortunately no. Without some form of source control or a functional back-up to go to you are kind of out of luck. As soon as you push execute on that alter statement you have changed that table/function/view/StoredProc. For future precautions you should probably have nightly back-ups make sure only the appropriate people have the user permissions required to make database changes. Also you want to make sure you have source control and are following a proper procedure for testing and deployment to make sure this does not happen in the future.