i try to take a video and rhe phone turns

"4.8 of 5 gb used"

That is your iCloud storage, how much space is left on your phone?

"all of a sudden-I can’t use the feature to flip the camera from the front shot to the back. Selfie mode to forward shot"

Try a forced restart.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN)

How much storage space is left on your phone?

How long is the video you are trying to shoot?