There have been many questions and confusions regarding SNAPS. So, if you find your SNAPS are not working, or you don't know how to enable SNAPS, then please check if your SNAPS are turned off, as described below. 

Open up SNAPS window by right-clicking on SNAP  option that you can find on the status bar at the bottom. 

The Drawing Aids window will appear. Uncheck  "No Snap" mode, and checkmark Turn "No Snap mode" off if any snap is activated. Click OK.

You can also uncheck  No Snap from Modes > Snaps found at top menu bar. Also, from this sub menu, you can select whichever SNAP you want to enable while drawing. 

Further, please note that SNAPS are not something that you can apply after once the drawing is made. Rather, SNAPS help you draw accurately by selecting the exact points in your drawing (at the time when you are drawing). 

For more details on this topic, please refer to the links given below.

https://turbocaddoc.atlassian.net/wiki/spaces/T2UG/pages/92143756/Running+and+Local+Snaps

https://turbocaddoc.atlassian.net/wiki/spaces/T2UG/pages/92143879/Snap+Settings