Visual FoxPro General
Looks like you have deleted the form.sct file.
In VFP forms (and most other objects) keep their metadata in a set of tables. These are a DBF format with another name. For Forms it is {name_of_your_form.scx and .sct).
SCX file contains the data fields and their structure. SCT contains the memo field (free text) information including the data on the properties and methods of the form. If you have deleted that file by mistake you have to restore from a backup, else the form information is lost.
If the SCT file is corrupted instead of lost, there are DBF-repair utilities out there that can attempt to bring the information back.
This is one of the reasons why backups, or better yet, a source control system is so important to have and use daily.
You may try to undelete deleted file (extension sct) with something like :
http://www.snapfiles.com/reviews/Restoration/restoration.html
and after you may try what Alex said, to use a dbf repair software.