...I've always wished that Voyager was actually lost for a while...
That's actually not easy to do even with today's tech. No matter where you are in our galaxy you'd be able to spot other known galaxies, which tells you which way is which. If you can spot enough known pulsars in globular clusters in the galactic halo you can easily triangulate your position from those and plot a course for home.
You'd have to destroy the computers so all the records of known phenomenon and any starcharts. Even then, it's really hard to hide the monstrous Andromeda galaxy, and if you can't spot it, then you know it's hidden behind the galactic center. One schoolbook night sky chart with Andromeda in it and anyone with basic math skills could figure out roughly where they are if they can also detect the direction of the galactic center.