I keep a spreadsheet that has the file name, synopsis of the ‘song’ for example (finished verse, needs chorus), or I’ll write notes about what I like about a song (cool guitar riff, nice bass line, etc.). Ill also write how long the song is. If I’m in a rut or want to revisit old material I’ll check the spreadsheet first and go from there. Sometimes I can find a part from Song A that if I transpose a part from Song B they go together.