If there is regular maintenance that is done on your garden then there is the posibility that a lawnmower or some other type of machine has damaged the head of the sprinkler. You will be able to tell because the sprinkler will either fail to come up or it will spray everywhere when it does come up.
Sometimes water does not come out of the sprinkler head because there is a blockage, over time, dirt, sand and other debris can block up the pipes and cause large issues for your sprinklers. If you wish to clean the filter then turn off the water remove the nozzle and filter and clean it,
There are a few reasons as to why this would happen, one could be that it fails to keep time, sometimes the time dial may not be turning, it will not change into manual mode, or all the controls fail to activivate during automatic mode, if these do occur it possible to search up how to reset in your system in the manual, but calling a proffessional can makes things much easier.