Is this an older machine? If so, I am wondering if you oiled it well before using it. The older machines have a lot of oiling points. If some of these points are not well-lubricated, the zigzag mechanism inside the machine (as well as the bobbin mechanism) may not work with accurate timing.
If this is a newer machine without oiling points, I'm not sure what to recommend. Typically if the needle doesn't pick up the thread, it's a timing problem.
Do you know if the machine worked before you put it into storage?