my 2002 Nissan altima every now and then will not shift into DRIVE!

If you want to get the correct answer and the least costly result - I promise you - that it will be well worth it to take it to a good Nissan dealer and after an hour or two of diagnostic time, you will know exactly what is wrong with your Altima, and what it will take to repair if correctly, then normally what you spent in diagnostic time, is usually deducted from the repair bill. I'm assuming you have not taken it anywhere. Have you checked to see if you have any transmission fluid left? Sounds 100% like a transmission issue. Avoid any shortcuts and only have a Nissan dealership do the work, and they use OEM parts, the right ones. Hope it works out.