Since you did not provide a model for your laptop I can only give you a generic answer. the continous beeping sound usually suggests a problem with a processor.
1. A failing Video card. Try an external monitor.
2. RAM, this is common Remove the ram clean it..
3. A Processor error, remove the fan and processor. Clean it and reapply thermal paste.
4. A Keyboard error. make sure that you do not have a stuck key. Try to start with a USB keyboard.
You may get a better answer if you can give us more information as for what model. Hope this helps, good luck.