All the black in my image has turned transparent, help!

[Ofnuts]

Cannot tell without seeing the image file (and even then...). Depends how you colored, and how you saved (exact options...). Black is considered the "transparent" color in some cases.

Also, why did you use BMP? this a very ancient and ill-defined format. Unless you are using the file in an application that requires it (and then you have to figure out which variant of the format it wants) you can use PNG instead.