First make sure you have copies of your radio / alarm codes etc.
Check the voltage of your battery.
It should read 12.6 volts fully charged.
Check your cable ends at the battery and at the starter. You may need to disconnect them for a good cleaning.
Check for a voltage drop when cranking .....Below 9 volts is a problem.
There is no true test for a battery.
It may read good but fail under load.
How old is it??
I had one battery last 11 years (motorcraft) and one last 8 months (die hard)
As you have described, it sounds like the starter may be faulty.
If you can....smack it with a hammer. In a tight place use a pipe to reach it and smack the pipe. This may jolt the amature and it may start.
Look carfully at the connection at the starter ....how does that cable look?
You can....with gloves, move the crackshaft by giving the belt a goog tug.
-Anthony