In the sticky thread in GQ that lists reference sites, somebody linked to the Melody Hound. I’ve never used it, but maybe you can try it and tell us how well it works for your tune.
It sounds to me like a study for Classical guitar. These were fairly simple pieces, designed to improve students technique but often quite good as music in for their own sake. Fernando Sor wrote a number of them as did many other composers for classical guitar.
The first chord sounds like D minor to me, if that helps you any.