//note: I don't use D3D11
MSDN page for D3DX11CreateShaderResourceViewFromFile says there is DirectXTex library, that should be able to load *.tga files using LoadFromTGAFile routine. You should give it a try. If it doesn't work for you, you'll have to write your own texture loader. (because it was possible to make your loader for textures in D3D9, it should be possible to do the same thing in D3D11). *.tga format is documented somewhere and many beginner tutorials specifically deal with loading this particular format without 3rd party libraries.
Two advices:
- Next time, when in doubt, read documentation.
- DON'T look at *.png format. This format loads very slowly (jpeg is faster, uncompressed bmp is faster, dds is faster) and most likely isn't suitable for games that need to load many images often (it is okay to use it for start menu, ending screen, etc). Either use uncompressed format (such as *.tga) or (since you're using directx) use *.dds format. Your images most likely will take extra disk space, but will load more quickly.