It's good. not epic or great, just, good.
Some people here are right, some are wrong.
You must need better hitTest functions, cause sometimes the character stops moving from the wall even if it is NOT touching it. and next, you need enemy(s). like a spider, a frog, crab, whatever.
Then add stomping points, where you hit the enemy(s) top and it disappears or shows a animation showing him to 'die' and add the removeMovieClip function at the end of the frame.
And, WASD isn't a good idea. i mean, it is, but still the player should be able to move with arrow keys and WASD. WASD for left-handed people, Arrow keys for right-handed people.
And the respawn points. you can add walls and no gaps, or add a respawn point so if the player leaves the stage, he re-spawns.
And if you are using tutorials and just stupidly copy-pasting, don't. you won't even learn!
I also did copy-paste on my first try, now what? I came to code it all myself.
And add objects like ladders, lava, moving platforms. the best place for this is: http://www.emanueleferonato.com/2007/
07/03/creation-of-a-platform-game-wit h-flash-step-1/ .
And, some good colors, even if it's black-and-white, add SOMETHING just colored, or add a old-school TV effect to it.
And don't make a part 2, or make one but with BETTER CODING.
Or, don't make a part 2, make another game series with better graphics, hitTests, and kinda stuff like that.
Or, learn AS2, even AS3. i recommend AS3, I don't use it cause i don't have it but i recommend.
Yeah, change the title, "Lost in a Platformer" isn't actually a meaning. make titles like "Lost in a cave" with cave graphics, "Lost in Hell" with Hell graphics, "Lost in a unknown world" with normal but good graphics, "Lost in Retro world" with retro graphics. graphics are actually made from names. if the name includes cave, it would be cave, cave graphics.
And the background, it should be better.
AND, make a scrolling background, with a scrolling code or V-Cam.
And make other things like bumpers, trampolines, bosses, spikes, and stuff.
You can mix up all tutorials to get up a great game.
find the hard and easy ones, mix them up.
You will get a awesome game, if not, try again, or if you have good coding skills, code it yourself, if not (looks like not), learn ActionScript.
Here, make the ball a guy, a stick-guy, a human, a alien, whatever.
Or even, make the ball stylish....
And, draw the level design on a paper, and then draw it.
You can check on E-How for some ideas, it doesn't show codes but ideas,
and then mix tutorials up.
And here's what it all ends on.
I'll PM you if i forgot something :P