I have run COMPACT/REPAIR with mixed levels of success. You want to run this operation consecutively about 10 times. (I know that doing the same thing repeatedly and expecting a different outcome is insane, but it often happens with MS Access). This is relatively low effort and should be attempted first.
When you get the DB working, you should verify that the DB is NOT set to "compact on close". Compacting on close always increases the chance of form and report corruption corruption.
If you ever find that you can open the form or report in design view, but it doesn't work in run time, you may have a corrupt control on the form. The only way I have worked around this is to open every form that uses the corrupt control, deleting the corrupt control, repairing the install of MS Access through the control panel, then readding the control to each form in the place where you deleted it. Leaving the corrupt control in place in even one form will prevent the "fix" from beign applied to all forms.
As all of the MS Access forums will tell you, splitting the data tables from the forms and reports will save you a lot of headaches by minimizing the risk that (the inevitable) form and report corruption will effect your data tables. Restoring can often be done in a matter of minutes by resessitating an older copy of the front end.
One final thought here, though the error generated is a little different, should the front end and back end are separate, moving the back end data tables, or renaming any folder along the folder path will break the link used by the front end to connect to the data tables. This can be fixed either by restoring the original folder names or storage location, or by using the LINKED TABLE MANAGER to repoint the front end to the linked tables.
