Low water pressure after turning main water back on
Have you opened all the other water faucets in the home and flushed the toilets? There may be water in the line. The only other idea is that your water heater and water softener unit may be trying to fill up, causing low water pressure. Make sure there are no other water leaks.

I too am not a pro but can figure things out. I had to replace the on/off valve on my toilet not to long ago. I could not afford a new one at the moment. So I turned off the water main, and removed the valve. I soaked it in vinegar over night. (I did this at 10pm to 6 am.) I filled my bathtub with water and used a small bucket of water in the bathroom and filled with water and poured it in the toilet to flush. I then re-wrapped the threaded connection and reassembled the valve. It wasn't perfect but it lasted another couple days. Then I replace with a new one.

You may want to consider putting in an on/off valve under the toilet. I have had to install several in my home as none of the showers had any.