I suggest trying to break it down by inning. Start off trying to win the first inning. If something goes wrong and you fall behind. Then start off fresh and try to win the 2nd inning and so on.
Are they not hitting or making errors? If the games are close then hang in there and make minor adjustments. They need to have a short memory if something goes wrong (error, strike out etc). Don't let them dwell on a mistake and keep them ready for the next play. Hopefully you are not letting them see your frustration. Keep them up and you'll start winning.

In order to start winning, look at the reasons why you're losing games and work on them at practice. Is it discipline? Work on keeping your team focused. Is it a lot of errors? Keep things positive. It's tough to stay positive sometimes but a happy team will be more likely to win games.

Overall, remember why you're there. Keep your team positive and keep teaching them. The wins will come eventually. My daughter played for a tournament team that got killed the first year they started playing. Most of the players stuck it out and kept learning and now they're winning in the 14U division with a group that consists primarily of 12 year olds.

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