It's probably the cartridge's fault. The battery might be empty, or there might be some other fault. For example, if you've ever opened the cartridge, you might have damaged a resistor near the top of the PCB. (Common problem on non-USB bleepbloop carts.)
If you can get the file off of the megamem, transfer it safely to the computer and end it to me, I can have a look at it. Maybe I can get something useful out of it. Of course, you should use a cartridge with a working battery for the transfer. You also should also avoid starting the LSDj version that i on the cartridge between transferring it from the Megamem to the cartridge, and from the cartridge to the computer.

My e-mail address is my username followed by @gmail.com.

Thanks. You know the really annoying thing is, I was going to buy a usb cart a few days ago & didn't. It's a sign. I'm definitely ordering some in the next month or so.

Try to get some new carts. 32M carts are ancient and if they are the EMS style carts, you will have to have a relic of a transferrer.

At the bare minimum for flash carts, I recommend getting the 64M EMS USB Flash carts. You can back them up to your computer via usb cable.

OK. I've tried everything & it's not coming back, I've cancelled my gigs. Thanks to everyone for trying to help.
Just so I know for the future, what is the best way to back up sav files?

& I can load another carts savs on the cart that got erased, so it's not the battery. I'm stumped.

So, I tried loading the backups for the hundredth time, & it loaded just the names of the songs but nothing else, so I tried again & it just came up blank again. I'm so confused.

http://www.maplin.co.uk/store-locator/worcester

Always backup your SAVs on multiple HDDs/SSDs.

I did try loading the savs in to another cart & it still came up blank. It's weird. I had 2 back ups of the same cart & ..nothing

i don't have any batteries. My only option is cancelling these gigs or trying to write a whole set by tomorrow. It's a 32M cart.

Clean:
DMG cartridge contacts
MMC contacts at both ends
Flash cart contacts

Try uploading SAVs onto a different cart.

Report back.

i would recommend changing the battery on the lsdj cart (if it is one that needs a battery???) then trying to reload with your backups.

this sounds like what has happened to me on multiple occasions. welcome to making game b0y music

@nitro2k01

Um, sorry, I was panicking. Basically, I turned on my gameboy to practice for tomorrow, & one of the songs on my lsdj cart hadn't loaded properly & was all messed up, it's happened before, which is fine, I have all my carts backed up on a mega memory man, but when I loaded the back up files from the mege memory man, it just loaded a blank lsdj cart, with no savs. Am I making sense? sorry, if you have any questions so I can be more clear I will try my best to answer them.

Can you be more detailed?