I left my 93 Ranger sitting for maybe a month while I was away for work.
When I came back I jumped it and it started up right away easy no problem. (I didn't take it anywhere but let it sit in the driveway and run for 15 minutes).
It's been 2 days since that initial jump and now it won't jump start at all. Not with cables or a standalone battery jumper. There's no clicking, no sign of lights or radio or anything at all. Just total and complete dead silence.

The battery was replaced maybe 3 months ago.

What should I check next?

 

Welcome to the forum

One or both Battery cables is disconnected from vehicles electrical system

Most people hook up jumpers or boosters to the battery cable ends on the battery
As they should
But if there is still no electrical power in the vehicle then one or both of those cables is disconnected or has a bad/corroded connection at the other end of the cable

In a 1993 the positive battery cable runs to larger post on Starter Relay(solenoid) on inner fender, it will also have several other wires and cables connected on that same post, this is the MAIN power distribution post for the whole vehicle
If it needs 12volts then its connected on this post including both fuse boxes
Disconnect battery positive at the battery FIRST
Then remove all the wires on that post and clean the ends and the post, then reinstall all the wires

Battery negative, often over looked, but there is no POSITIVE unless there is a NEGATIVE thats the way electricity works, it must FLOW from one terminal to the other or there is no power, no current, like current in a River, if there is no flow then its a LAKE, lol

You can hook up jumper cable to battery positive then hook up the negative jumper to Engine metal, bare unpainted metal
If you now have power with key on then Battery negative cable is the problem, clean its connection to battery AND other ends of its cables