Check your battery voltage first, if the voltage is fine, check the starter by trying to manually crank it.
On your starter solenoid, you have the large main voltage terminals, and the smaller starter trigger terminal, pull the plug off the terminal, and take a set of jumper cables and attach it to the positive terminal on the battery.
Then just tap the cable against that trigger terminal to momentarily supply 12v to it to crank the starter. If it cranks, then there's something going on in your ignition circuit that you;ll need to diagnose. Could be a bad connection, fuse, bad switch, etc.
If it doesn't crank, then it's the starter/solenoid.