Hi there! I'm really sorry about, this is what usually happens when a computer doesn't have the requirements to run the game (1GB graphics card, 4 or 8GB of RAM and 2 Ghz Dual Core, and we recommend having windows 10, but it can run on win7+ if the other requirements are met).
Sometimes it can happen on computers that do have those requirements but that are running other resource heavy programs at the same time, like screen capture software or other things that use your graphics card. In that case, it's best to close those other programs, but it's possible that you might encounter visual glitches and missing sprites again as you play :(