I had the exact same router (still have one), but usually when that happens it is bricked (trashed). Most likely it is time for a new one.
That happened to me once when i was on with a tech support guy who suggested i try updating my firmware to solve an issue. It stopped half way through and that was it for that router. Luckily since they told me to do it (my ISP) they had to replace it with a new one.