Shifts Into gear but will only Rev

What is your question?

When trying to install some speakers the battery died. when we jumped the car when noticed that when we tried to take the car for a test run, it would shift into gear (example reverse) it when into the gear but wouldnt reverse. Wont drive nothing but reving. We did have the E brake on but even when we took the e brake off it will not go. I was thinking maybe we blow the safety sensor... or a fuse... I have no idea. And help?