Saves are stored on your computer, so if they got erased, something on your computer unfortunately deleted them -- the main reason is ONE of your web browsers deleting cookies when it closes (it doesn't even have to be the same browser you use to play), though some other software like CCleaner can remove them too.
Yes, this game is easy, and this would be much interesting if you put some sort of missions with different maps and with different enemies.
Thetominator, press Space if you want to leave upgrade screen.
First: game very short, make more lvls and add bosses. 2nd: you should be able to press mouse button to shoot, and hold mouse button to AUTOSHOT,not clicking all the time to shot rapidly. 3rd: need upgrades, no one would play shooter game without upgrades. 4th: AI should be smarter then just flying in circles and shooting at you,+ need a bit better graphics.
That was my suggestion to you, if you can do it, everyone would play your games, and 3/5 for this game, just because it is your first game.
Kill them ! :p