Problem uploading

hi all! i am getting frustrated with my site. i think i have 3.0 but cannot upload images or pdfs. it allows me to select browse and find my find and hit open, but then goes blank and nothing uploads.

our site is only updated periodically and i haven’t had any success in uploading files since the end of december. please excuse my ignorance as i didn’t set up the site, i’ve inherited it.

any help you can provide would be great!
thanks!