There are several reasons why your camera will not record and they are as follows:
1. MEMORY CARD FULL
Your camera will not record if the memory card is full and has been set to non-circular recording (does not overwrite old files when memory is full). In order to record again just take out the microSD card from the camera and delete some old files or set the camera to circular recording then re-insert the microSD card to the camera to start recording. You can also set the camera to circular recording then format memory card (clear microSD card's memory) then re-insert.
If the camera is already set to circular recording just go ahead and format the memory card then re-insert it to the camera to start recording.
2. MEMORY CARD DEFECTIVE
Another possibility why you can't record with your camera is the microSD card inserted is defective. Remove the microSD card and try the card to a different device that uses memory card. If it works on a different device, format the memory card then re-insert it to the camera and try recording. If still can't record, press the 'R' button on the camera to reset the unit then try recording again.
If the microSD card does not work on a different device, please go ahead and try a different microSD card.