Accidentally deleted my purchased song, would I be able to download it again?

KPS,

If you are still using the same Apple ID, are in the same country, and the content is still available, you may be able to redownload fresh copies at no charge. Follow the steps in here:

Redownload apps, music, movies, TV shows, and books - Apple Support

By the way, if you deleted it from your iTunes/Music library on your computer, you can just get it out of Trash/Recycling and add it back to your library.

KPS, You are welcome. :-)