95 mazda

Possible causes are :

1. Battery is bad or has poor cable connections. Try a jump start to see if it works.
2. Bad starter or connections. Give the starter some knocks and test if it works. Disconnect the soleanoid wire and use a remote wire to apply battery voltage to the terminal to test if starter works.
3. Bad ignition switch.

Which model van do you have and the engine capacity?

Another possibility, if starter motor or earth/wiring/solenoid all OK.
Timing belt may be broken, valves fouling piston(s) preventing motor
from turning. remove tappet cover and try to turn motor backwards
while observing camshaft/valves. Non movement will be self explanatory.