Ok everyone i had this problem two and sat here reaing North Poles advice and while doing soo i accidently cam across the solution please follow the given steps,
1. open settings/general/accesibility
2. turn off it dosent matter if u slide it or click it, coustom vibes and LED flash for alerts
3. hit the home button
4. X2 click the home button to bring up the multitasking menu
5. clear all the apps even settings by hitting and holding them untill they shake and hit the red minus arrow.
6. after clearing all the apps shutdown the phone it dosent matter if u do a force shut down or normal safe shut down.
7. start the phone back up.
8. when the phone boots give it a second to chatch up then unlock and go to settings/general/accessibility
9. turn on LED flash for alerts.
10. set a one minute timer or send a text and when the phone is LOCKED the LED will flash.
11. after testing the flash u can turn back on the coustom vibrations and the LED will still flash
Hope this helps!