My gosh, things keep piling on. I thought I was going to do a quick replacement of my refrigerators shutoff valve. Went downstairs to turn off the main and it doesnt even budge. It appears as if I turns downwards into the wall. I could solder it, but I dont know how to purge the line of water. I could even do a sharkbite (ive read that they are up to code for mains which I didnt know) but...how should I do this? I dont really know how to deal with the turn. I should (and probably will) call a plumber but I really didnt want to spend so much money. Thanks for any advice.

 

I added an arrow to your picture. Try loosening the bonnet nut and see if the valve turns.
Start with half a turn counter-clockwise.
There isn't much room to work there and no room for a sharkbite valve.
Look into what's causing that corrosion too.

Regardless of info found.... I wouldn't want a sharkbite valve as my main shutoff.

 

Put a large adjustable channel lock pliers on it to turn the TOP of the valve. (It's red). That's a good quality valve, it just hasn't been turned in a while so its tight.

If you don't have one, buy one. There is no reason to even think about calling a plumber as long as you can shut off the water yourself. And you should be able to do it with a big enough pliers.

 

 

You need to do a bit of demolition and make the access opening bigger. You want it large enough to swing a wrench and get a screwdriver onto the end of the knob.

If you can't easily free the valve I would turn the water off at the street. Then open a faucet to relieve the pressure. Since you now have a big enough access to work remove the screw in the end of the red knob and pull the knob off. Then hold the valve body with one wrench and use another wrench to loosen the larger hex (to the left of the arrow). This will allow you to pull the guts of the valve out. Then you can clean up the mineral deposits and get the moving parts moving again. Then reinstall into the valve body and turn the water back on at the meter.

You also have a leak. It's probably the bottom solder connection to the valve. When you have the wall opened to make access better you will be able to more easily see the source of the leak. With that amount of corrosion I'm guessing the fitting (elbow?) should be replaced and not just re-soldered.

 

The "leak" kind of looks to me like silver solder dripping out of the joint, (normal) and fiberglass (with plaster dust) packed around the bottom of the elbow as a cushion.

 

First of all, who was the jerk who put the valve in that direction. He should be shot.
Second, I would not force that handle with wrench. If it's seized, results could be disastrous. It's worth calling the municipality to have them shut-off the valve buried in your front lawn. Then relieve the pressure and install a quarter turn ball valve.
If you're brave enough you can buy the special handle to turn off the outside valve yourself (most cases, it's illegal). In some municipalities your required to hire a licensed plumber. Again, if you're confident enough, DIY.
If it's exposed at all times, a SharkBite valve would be OK. But I agree I would not want it in that situation. If you force that handle and the stem and or seals break, you'll have quite the mess and try getting a plumber to come out on the spur of the moment.
If you want trouble free for the rest of your life or life of the house, do it right, install a ball valve.

Another alternative...if you can get the existing valve to at least shut the water to a slow trickle, you can open up the wall several inches and install another ball valve up stream and that will become your new main, and never ever touch the old valve once it's turned back fully open.