ERRO INICIAR O XAMPP

Meu xampp estava funcionando normalmente, mas ai hoje apareceu esse erro.

13:49:33 [main] Initializing Modules
13:49:33 [Apache] Problem detected!
13:49:33 [Apache] Port 80 in use by "Unable to open process" with PID 4!
13:49:33 [Apache] Apache WILL NOT start without the configured ports free!
13:49:33 [Apache] You need to uninstall/disable/reconfigure the blocking application
13:49:33 [Apache] or reconfigure Apache and the Control Panel to listen on a different port
13:49:33 [mysql] XAMPP MySQL is already running on port 3306
13:49:33 [filezilla] Problem detected!
13:49:33 [filezilla] Port 21 in use by "C:\\Windows\\system32\\svchost.exe -k ftpsvc"!
13:49:33 [filezilla] FileZilla WILL NOT start without the configured ports free!
13:49:33 [filezilla] You need to uninstall/disable/reconfigure the blocking application
13:49:33 [filezilla] or reconfigure FileZilla and the Control Panel to listen on a different port
13:49:33 [main] Starting Check-Timer
13:49:33 [main] Control Panel Ready
13:49:35 [Apache] Problem detected!
13:49:35 [Apache] Port 80 in use by "Unable to open process" with PID 4!
13:49:35 [Apache] Apache WILL NOT start without the configured ports free!
13:49:35 [Apache] You need to uninstall/disable/reconfigure the blocking application
13:49:35 [Apache] or reconfigure Apache and the Control Panel to listen on a different port
13:49:35 [Apache] Attempting to start Apache app...
13:49:35 [Apache] Status change detected: running
13:49:36 [Apache] Status change detected: stopped
13:49:36 [Apache] Error: Apache shutdown unexpectedly.
13:49:36 [Apache] This may be due to a blocked port, missing dependencies,
13:49:36 [Apache] improper privileges, a crash, or a shutdown by another method.
13:49:36 [Apache] Press the Logs button to view error logs and check
13:49:36 [Apache] the Windows Event Viewer for more clues
13:49:36 [Apache] If you need more help, copy and post this
13:49:36 [Apache] entire log window on the forums