MAC APP STORE APPS WILL NOT INSTALL

I am having problems with my mac apps not installing. i'll purchase the app and it will go into the downloading bar in my dock. no progress will me made on the download but it will state it's installing. in the app store under the purchases tab the app will be listed as if i never initiated the install download. when i click to install the button will change as if i am starting to install it, but after a few seconds will change back as if i never clicked it. i am running a outdated OS but i've tried to install Mavericks but the same problem occurs as with the apps. I am currently in the military overseas in Afgnanistan so going to an apple store isnt an option and makes things like calling the support center difficult. Thanks for the help.