I was used to connect to my EC2 instance through Putty to run a bot. Suddenly, it wasn't working anymore: the 'request username and password' lines weren't there anymore and I was getting a 'connection timedout' error. So I went to 'my instances' in EC2 AWS console and it says 1/2 status check failed: "Instance reachability check failed". How to fix it?
Go to AWS services menu and select EC2. In the left side menu, select "instances". Then, in the instances list, click on the checkbox of your faulty instance. Then, with this instance selected, click on the button "instance state" then click on 'reboot instance'. You will see a green message saying that the instance was rebooted. Wait a couple of minutes and try to connect to it from Putty again. This time it should work.