Hey sidd2312,
Thanks for using Apple Support Communities.
Sounds like you are not able to open the Facebook app and another app. It could be a larger issue than just Facebook so you can follow the second article and test after each step.
iOS: An app you installed unexpectedly quits, stops responding, or won’t open
http://support.apple.com/kb/TS1702
iPad (Wi-Fi + Cellular Models): Troubleshooting a cellular data connection
http://support.apple.com/kb/TS4249
Reset network settings: Tap
Settings > General > Reset > Reset Network Settings.
iOS: Troubleshooting Wi-Fi networks and connections
http://support.apple.com/kb/TS1398
iOS: Safari web settings
http://support.apple.com/kb/HT1677
Follow these steps to clear information from your device:
- To clear your history from Safari, tap Settings > Safari > Clear History.
- To clear all cookies from Safari, tap Settings > Safari > Clear Cookies and Data.
- To clear other stored information from Safari, tap Advanced > Website Data > Remove All Website Data.
Have a nice day,
Mario