Recover deleted build result
One answer
A deleted build result is gone for good and cannot be recovered without doing a full database restore (which is a really big deal).
Permission to delete a build is result is listed under Team Configuration > Permissions > Build > Delete Build Result (server). There are separate settings for deleting the results of regular builds and personal builds.
You can also prevent the deletion of individual build results by unchecking the "Deletion allowed" box on the Overview tab of the build result.