Arduino Build Folder

I'm pretty much a novice with Arduino coding, so may be you could help me out. When ever I try to upload a program, an error message comes up, saying "Build folder disappeared or could not be written." I went through everything, to make sure it was correct (which it was), but it still showed up. Then to make sure it wasn't me, I opened up the example called "Button" and yet again, the message popped up. I know now it wasn't me, so could someone tell me what's wrong and how to fix it?

Try re installing software first or compiler suite If your using windows de install then reinstall possibly where the problem is Short of this Ideally we need to know what compiler suite you are using other wise none of us are any the wiser

What are you calling a "Build" folder?

Build process
Sketches are compiled by avr-gcc.
The include path includes the sketch's directory, the target directory (/hardware/core//) and the avr include directory (/hardware/tools/avr/avr/include/), as well as any library directories (in /hardware/libraries/) which contain a header file which is included by the main sketch file.
When you verify a sketch, it is built in a temporary directory in the system temp directory (e.g. /tmp on the Mac). When you upload it, it is built in the applet/ subdirectory of the sketch's directory (which you can access with the "Show Sketch Folder" item in the "Sketch" menu).
The .c and .cpp files of the target are compiled and output with .o extensions to this directory, as is the main sketch file and any other .c or .cpp files in the sketch and any .c or .cpp files in any libraries which are #included in the sketch.
These .o files are then linked together into a static library and the main sketch file is linked against this library. Only the parts of the library needed for your sketch are included in the final .hex file, reducing the size of most sketches.
The .hex file is the final output of the compilation which is then uploaded to the board. During a "Verify" the .hex file is written to /tmp (on Mac and Linux) or Documents and SettingsLocal SettingsTemp (on Windows). During upload, it's written to the applet sub-directory of the sketch directory (which you can open with the "Show Sketch Folder" item in the Sketch menu).

Sometimes if errors are produced some compilers automatically delete the build libruary if you have clean option ticked in the compiler settings

This happens and if an error is poduced You should have a reports telling you if the build completed hence why Im suggesting re install the compiler first But normally you see an err.log or the complier reports a fault

Might Just pay to set up a new project first pick some example code off the net somewhere and see if it will compile
Thats the best way to tackle this problem