The simplest way is to obtain it from your most recent backup.  When I am
"heavy into" development mode, I make a backup copy several times a day --  
determine the timing of your backup copies by the amount of work that you
are willing to repeat.

Save a copy of the failed database as a baseline reference (if none of the
suggestions work, then there are some third-party data recovery operations,
one being http://www.pksolutions.com, paid recovery but free estimate, last
I heard).

Each time, working on a copy of your baseline reference:

1. It is sometimes possible to recover a form by Compact and Repair, I am
told -- I never was able to accomplish it that way, or

2. Decompile and recompile, or

3. Create a new, empty database and import each of the objects from the
corrupted one, or.

4. Use the officially-undocumented Save As Text / Load From Text features.

For more information on #2 or #4, visit the Google Groups newsgroup archive
website and search this, microsoft.public.access.forms,
microsoft.public.access.formscoding, and the USENET newsgroup
comp.databases.ms-access for details.

5. If none of these work, you'll have to punt, er, contact a data recovery
service.  The only one on which I have had consistently good feedback is the
one I referred to earlier, http://www.pksolutions.com.

Larry Linson
Microsoft Office Access

Quite often in A2003 when this happens to me a decompile fixes things.

Decompile or how to reduce Microsoft Access MDB/MDE size and decrease
start-up times
http://www.granite.ab.ca/access/decompile.htm

Tony