@Winchestergirl
You could be asking everything from how to open an RMVXAL file with Lite or how to open it with the full version of Ace. You could have accidentally deleted your file, and you could have accidentally moved it to another location and tried opening it from a location-sensitive shortcut. We would never know what exactly you need help with, and what you did, without you giving as many details as to what you are doing and what you did before.
That being said, a good title would be a very brief descriptor of your problem, like 'Unable to load Lite project' or 'Accidentally deleted Lite project file' based on the context of the situation. The main body of the post should contain a reasonably concise description of the problem you're having, particularly what you are experiencing, what you have attempted, if anything, and any extra details that might help. I know what it's like to panic when you screw something up, it happens to everyone. I once overwrote a project with an old backup when nothing was wrong with it and lost months of progress. I only just recently learned you can restore previous versions of a file, though I have yet to find an applicable use for it in regards to RM files.
Take a deep breath, as long as you don't do anything thoughtlessly, your file will not be inaccessible forever. Panic is not your friend, it is your enemy, and will make you act in a useless manner such as this. I'll keep an eye on this thread so I can offer help after you've given more details.