I upgraded to OS X 10.9.4 and my Autocad not open.

Question

After updating, my AutoCad not open. What can I do?

Answer 1

If you don't already have a current backup, back up all data. There are ways to back up a computer that isn't fully functional. Ask if you need guidance. You can skip this step if you don't care about the data that hasn't been backed up.
Reinstall the OS.* Your data should be unaffected unless something goes wrong. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used.
If you use FileVault 2, then before running the Installer you must launch Disk Utility and select the icon of the FileVault startup volume ("Macintosh HD," unless you gave it a different name.) It will be nested below another icon with the same name. Click the Unlock button in the toolbar and enter your login password when prompted. Then quit Disk Utility to be returned to the main Recovery screen.
If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data will be preserved.
*The linked support article refers to OS X 10.9 ("Mavericks"), but the procedure is the same for OS X 10.7 ("Lion") and later.