If your GPU was made before 2010 (like the Nvidia GeForce 200 series or Intel HD 3000), it may physically lack the hardware to support Feature Level 11.0. However, for most users, a simple or Windows Update will clear the error and get you back into the game.
covering new HLSL profiles (vs_5_0, ps_5_0, etc.) and features like dynamic shader linking and structured buffers. DirectX 11 Technology Update US : A technical presentation available on D3d11 Gpu Feature Level 11.0 Shader Model 5.0 --FREE