I'm sorry to hear that you're having problems with this! I'm actually trying to gather some information on what might be a problem for a few customers, so if you don't mind I'll ask you a few questions:
You can upload images from a few different places in our interface. Which one were you using? The Media Library, the new editor (Go to WordPress.com then click the pencil icon in the upper right hand corner and add media there), or the old editor (Go to your Dashboard and then Posts and then Add new and add media there)?
Could you walk me through the entire process when you do try and upload and let me know when you stop getting results?
What browser and version are you running? Also what operating system and version?
Thank you in advance!