In order to understand the problem of why Minecraft stopped working you need to think back to before it stopped working and what changed. Did you install any mods? Did you try to use a texture pack? Did you update drivers? As Minecraft is updated mods and texture resources may cause frequent issues.
Usually in any case your best solution is to find your .minecraft folder and delete the bin folder inside. You can either use the search function in the windows explorer, or browse to something like:
The AppData folder is a system folder, and probably wont show up for you. In the control panel there is a section for Folder Options, and you can check or uncheck the ability to display hidden system folders. Even if it is hidden you can always type the folder path into the address bar.
Once you delete the bin folder the Minecraft client will download all the needed files and remake that folder.
i already deleted the bin file, still crashes. this happened shortly after beta came out, around 1.01 or something. i haven't installed my texture pack nor updated anything on my pc other than the game ;[
Sorry to hear you are still having troubles. I can only suggest updating your graphics drivers. A black screen is usually graphics related.
If you want to do that and get best results I suggest the following(unless you have a newer ATI/AMD card that supports auto driver updates):
1. Uninstall current video drivers and reboot.
2. Head over to Guru3D and get the driver sweeper. Install it and remove anything leftover from your graphics drivers.
3. Reboot, and download latest drivers.
4. Install drivers and reboot.
This process is tedious to be sure, but it works. I used to do this every time I updated drivers. Hope you can get back to your Minecrafts soon.