APR files are ArcView Project Files from ArcView 3.x. The new (9.x and 10.x) versions of ArcGIS are unable to read these files. Although ESRI no longer supports, ArcView 3.x, APR files can be imported into ArcGIS 10:
- In ArcMap, click on Customize > Customize Mode > Commands.
- Type "Import from ArcView project" and select that command.
- Click and drag the command onto any toolbar in ArcMap. Click Close.
- Click on Import from ArcView project in its new location, and specify the APR file. Also specify which layout you would like to import. Click OK.
- ESRI: Importing an ArcView GIS 3 project into ArcMap 9.3
- Nebraska Game and Parks Commission: Import ArcView 3.x project to ArcGIS 10