You have two...you could make a Y cable, shorting the middle pins together (outer pins are ground/+5, inter two are data), and combining both chargers to make a 1 amp charger.

Really though, a 500mA charger should do the job, it will just take longer. I used a 500mA charger for months, since I left my Nokia at a relatives during a trip. It takes a bit longer, but it should still charge. If it's not charging at all, I would check that the converter cable (micro to mini) works. Those tend to have a high failure rate when it comes to being manufactured right. I bought 3 before I found one that worked.