One place where airbag wires sometimes come loose is under the seats (occupant sensors). This can happen if you have stuff rolling around on the floor, move seats around a lot or stuffed something under.
There are deployment modules and airbag sensors all over the place. Checking all the connections to those would be a huge undertaking. Your best bet would be to get the code, since it will indicate which component is not working correctly. Once you find out which component it is, you can then start checking for loose wires.
In order to get the DTC codes you need a code reader. If you do not have one, you can try going to Autozone as they will usually read codes for free. For airbags, the check engine light does not come on, only the airbag indicator light.