Preston Benedict

2 years I built this bridge and added some sculpted railing using a freebie sculpt map I bought on the marketplace. The bridge sat nicely on my lnd all this time until last week when the object just turned back into a torus. At first I assumed that the sculpt wasn't rendering but after this persisted for days I asked friends to come look and it didn't render either. Once I checked properties I saw that it was no longer a sculpt and had reverted to a regular prim torus. I've reapplied the sculpt map and it's fine again but I've never seen this happen before and wondered if anyone else had experienced this phenomenon?

I am rolling back from V2.8 (which doesn't run on my PC) to V2.7.1. Are there any steps or precautions I should take to ensure that none of my preferences or outfits (very important) are not lost?