I get that: getting stuck on something, losing all interest, and just stopping altogether for a month or two. Happens to me from time to time.

Genki, for example, did a pretty awful job of explaining verbs. I bet a lot of people gave up right at that lesson. I myself have re-learned the verbs at least three times now. The first time, I learned all of them in the ます (masu) form. To conjugate, you just drop that and add another ending like ました (mashita) for past tense. That was a really bad approach :D But hey, it got me to learn 15 or so commonly used verbs.