Simply copy/pasting an error message is not acceptable. Please provide a FULL and CLEAR explanation of the problem, including exactly what you're trying to achieve, how you're trying to achieve it (relevant code) and what happens when you try (error message and location).
That said, that error message suggests a situation that we won't be able to help with based on information about your application alone. It sounds like there may be an issue with the SQL Server instance you're connected to or maybe the network. I would suggest searching the web for that error message to learn what scenarios usually lead to it and what steps you can take to remedy them. We may get an idea form your connection string, so that might be somewhere to start, but I suspect that there will be a bit of trial and error on your part to find what works in your specific case.