The beeps are a positive sign : it should indicate that your CPU is working.
Can you see the IBM logo displaying (before the OS starts) ?
Maybe your RAM sticks moved a little and not correctly plugged anymore.
Unscrew the screw that locks the small memory compartiment on the back of your laptop.
Touch a mass of metal so that the static electricity on you can go away and will not damage the RAM stick. Then, unplug the RAM stick. To remove the RAM stick, you'll need to apply an angle of about 30° relative to the back of your Thinkpad.
In a first time, try to reboot your laptop without the RAM stick you removed.
There is normally a second RAM stick below the keyboard, so, your laptop should start.
If your OS displays, it means the problem came from the RAM stick you removed.
Then, try to re-insert it correctly and see if your laptop still works.
If the problem is not due to the easily accessible RAM stick, replug it and unscrew the screws numbered "3" so that the keyboard is unlocked. A keyborad symbol is also engraved on the back of your laptop near those screws. Then, open your laptop and softly remove the keyboard. You'll find the second RAM stick. below the keyboard.
Do the same as for the first RAM stick.
If things still do not improve, this could possibly be due to a defect Graphical Processing Unit (GPU).
My T43p beeps if I remove all RAM from it.
With RAM (I tried using just one stick also) it don't beeps... just fan, leds and a blank screen: no boot, no IBM logo
Can I replace just the GPU unit... or I need to replace all MB?