If you've recently added or tried to add additional memory to the computer and have started getting these beeps. Remove all new memory you've added to the computer. If the computer works fine after removing the new memory you're encountering either an incompatibility or defective new memory.OR
Sometimes when the computer is moved and/or over time a memory stick can become loose causing the computer to be unable to read the memory or get errors as it's reading it. Try fixing this issue by opening the computer removing each of the memory sticks you have in the computer and then placing them back into the computer.
If you have access to another computer that uses the same type of memory try using its known good memory in your computer.OR
If another computers memory works you know that you have bad memory. If another computers memory does not work and it is compatible with your computer unfortunately your motherboard and/or the slots on the motherboard are defective causing it to be unable to properly read the memory, which means the motherboard will have to be replaced.