Lost keystore alias but have file and password used for alias

Open your key store (.jks) file with text editor. It will display binary form of data. The readable text in the first line is your key alias.

For example, your key alias in the following binary data is the key alias.

þíþí your key alias UYY_ 0‚þ0 +* ‚êa÷í–ØRö}ðžá䶈ùÎL\ô©2‘wå¥H¨V †¸®Àµ£ð×þ7—â;TÁÙcsª”ž˜4ÝÉ'AÀì,’„×S¼ðßÅ'€Õ¡ó‚˜ ö!y’Çåx|(woÁh4u-û†‚‡§Qȸ|ˆ³”ÜæûZŽ²a±O­´¢^À.ªbÅ“e†6 É秮j§˜y ößÿØ0Çd@ /Ã?®¦ìé¼/§Zq””Ê•©„=~Ùì¢>º}DàO<Ö¹SbpÎŒ@Ø„°^Í^e»>¾ü«nM( "Nbûh·2ðÁ0¯ç¿61êè“[.ÇzeYŽºXkuÄy*ôq¥FSs]:2“ì

You can list the contents of your keystore with the command:

keytool -list -keystore <name of keystore file>

To do this, you will need to provide the keystore password (not the alias password). This will tell you the aliases in the file, which are self-contained, allowing you to sign. If you wish, you could also extract keys using other options / tools.