How to fix pc not loading anything, can load certain things such as task manager, but will take 5 minutes to load just for it to say no connection?

I was using my pc this morning perfectly fine, running game’s perfectly and even using the web-browsers fine. I then left my computer running whilst i was out and i come back went to close the game i left open and then nothing loaded after that. i’ve looked through many forums and still can’t get to the bottom of it, i can launch the pc fine and get onto the desktop, i then go to load a web-browser and it will take 5 minutes to load and then will just say error. it can load certain things like task-manager, but anything such as steam will take 10 minutes to load and then say i have no connection although i have an ethernet and it’s saying i have wi-fi in the bottom right. I then thought it was a hardware issue so i took my pc apart and couldn’t find any loose wires or anything fried so i put it back together and the same thing happened. i created a new user on my pc as i see someone mentioned that working but the exact thing happens, it will take 5 minutes to load the web-browser just to say i have no connection. i have multiple friends aswell as myself who have had pc’s for 7 years or so and have never had this happen before ?