There are many site. It is not appropriate to put forward individual sites as the "best sites but see the links below for some suggestions from contributors.
Note: Answers should not contain links in the text. Future contributions should use the related links facility to put forward suggestions.
Mp3 Sites
mp3ify
The best mp3 songs to download depend on your own preferences. Do you like jazz, rock or classical? Some sites have free downloads such as: www.ez-tracks.com. Other sites are paid sites like: www.amazon.com/MP3-Music-Download/b?ie=UTF8&node=163856011
Most mp3 file sharing sites. Bee mp3 is the best site for downloads.
There are a few sites where one can download free mp3 music. One can download for free from sites like 'mp3 Lemon', 'Indiamp3', 'Last.fm' and 'Music Dumper'.
go to meep.com and download it
4Shared is a popular MP3 download app for Android. Another is Music Download Paradise.
There is currently a wide range of sites which offer free MP3's. However, there are also many sites which contain scam downloads. To avoid any copyright issues, your best bet is to research which sites offer free samples.
I have found that you can indeed download music free in a legal manner. There are a number of sites that offer free mp3 downloads. Some of these sites are MP3.com, Last.fm, and you can also download them free from Amazon.
You can search for wedding blogs and look for playlists of good songs to play at weddings. There is a lot of mp3 sites then you find and download the song list.
Reverb Nation and Last.FM are good sites to download free Hindi songs. Download Hindi MP3 is another good site to download Hindi songs.
I'd suggest looking on YouTube for the download link. Also, many MP3 sites should have this song to download.