Remote access

When I remote access into my computer (from home to business) i cannot control the mouse. I try to control the mouse on the host computer however my screen is not working appropriatly on my host computer. When I try to turn on the screen it says "no signal" I cannot turn the host off because it is the server station that is needed in order to run the 2 cas registers at my store. I am scared that if I turn it off i wont get it back on. I have switched out the mouse and moniter with other ones. I have no idea what to do. Can anyone help? Please understand I dont know computers as well as most people on this site so go easy on me!