No game file stories, but I lost my phone which had a memory card in it that contained like 5 years of memories.....

:(

Oh, man! The OP story is pretty much identical to mine.

I was a young kid and I was playing Final Fantasy IX....I had to save, and I saved my game on my brother's file. My brother was at a good 80% of the game, while I was just at the middle of it.
I can remember that I couldn't touch the PS for at least a month, and my brother was mad at me for a lot of time....a lot of time.
We still don't talk about that accident, it could dig up some bad arguments, even though it happened pretty much ten years ago.

My old gamecube memory card (with save data for all my GC games ever) got formatted when I used it on a Wii from a different region, didn't really care at the time though XD

roffles XD

My every single 360 save got lost when I used the transfer data kit from my elite to my new slim - so that's every game prior to the 1st of January this year, lost.

Some of the ones that I am more pissed about than the rest;

Veteran campaign on COD4, had 2/3 levels left before full veteran completion. (I was doing the Safe House mission which took me an eternity to do, and was on the last stage at the farm where you need to extract at the bottom of the hill, I died about 1238128 times getting there, and trying to leave there. So I was pissed when I lost that.

Progress on Black Ops veteran campaign, done about 3 of those levels.

Dragon Age 1 - had about 3/4 saves of 20 warrior/mages and had 19 rogue I think.

Dragon Age 2 - will have to reply that abomination as well.

Mass Effect 2 Insanity perfect playthrough along with all the DLC playthroughs. Had to use the standard ME3 story template, couldn't import(rage)

Crackdown 1 & 2 5 star characters. All gone.

AC I/2/Brotherhood/Revelations

A fuckton of other game saves as well.

Ahh I deleted my brother's NFS Underground save cause I thought after going to college for the first time, he wouldn't care enough about it.... Came back for Christmas break and I didn't get to hear the end of it.

Another time, I was playing a new game on my brothers Pokemon Crystal file but I WASN'T gonna save it. I went to the bathroom at the same time my neighbor showed up.

"Hey, I saw you went to the bathroom, I wanted to play Def Jam: Fight For New York, so I saved your game for YA! :)" Man...the look of disappointment when I had to reveal the news...haunts me to this day.

I lost once my Pokémon File cause I went to sunny town. It was somekind of cheat.
And once I lost my favourrite Def Jam: Fight for New York Character because I turned the system off while it was saving. Both times i wanted to kick my own ass :S

I was a game tester at Activision for Tony Hawk's Project 8 for both X360 and PS3. I was a 'runner', someone who could run through the game faster than anyone, and could execute any challenge throughout at a moment's notice.

On this particular day I was working on the 360 side of things when another tester needed one last challenge to be completed in order to successfully finish the game. He'd been trying for around 20 minutes but couldn't do it, so I came over and first try did it. The save prompt came up, but I didn't realize that it was opposite of the X360's, which I had become more accustomed to. (the UI was always changing, and on this day the overwrite file option was different from the day before). So I chose the wrong option and I completely wiped out all of his progress. I think it took him an hour or two to get back to where he was. That was really the only mistake I made during the testing process, but I can still feel the sick feeling in my gut after I killed his save data...

...and that's why I use Android and have everything in Google services.... i.e. the cloud. Nothing on my phone (or PC now) can be really lost to me.

phantasy star online gamecube, had 100h on it before my internet was conected. logged online and file corrupted due to save being on third party mem card