ERROR APACHE

[[:Antonio:]]

Error: Apache shutdown unexpectedly.
21:24:52 [Apache] This may be due to a blocked port, missing dependencies,
21:24:52 [Apache] improper privileges, a crash, or a shutdown by another method.
21:24:52 [Apache] Press the Logs button to view error logs and check
21:24:52 [Apache] the Windows Event Viewer for more clues
21:24:52 [Apache] If you need more help, copy and post this
21:24:52 [Apache] entire log window on the forums

how do I fix without changing port?