I have noticed that after doing a Windows Update in Windows 10, it sometimes disables or removes drivers it considers outdated. This time, it disabled my SQL Server instance and I can not connect to the database.
When you try to connect, you get the message given below.
I was also getting an error, when I was trying to run my application: 'The underlying provider failed on Open'.
The application was running fine the previous day and suddenly it was throwing these errors. I checked the connection string, rebuilt the solution and also did a GIT pull to check if I missed some changes.
On further investigation, I realized that SQL Server Service was not running and was in a stopped state.
To re enable it, open run. ( Press Windows key + R ).
Type Services.msc and press OK.
A Services Window opens, scroll to SQL Server. ( Be careful not to change any other Services).
Double click on it. Now, click on start.
Service status should change to running.
Note
If startup type is disabled, change it to automatic.
I believe this happened because I was using an older SQL Server instance. Ver: 12.0.2269.0
I hope this blog helps someone.