1994 Nissan d21 no speedo and won't shift.

[94d21vg30]

Hello everyone! Been creeping around on this site for awhile gathering all the awesome information I can but finally need specific help with an issue. I own a 94 Nissan d21 v6 automatic with 4x4 96,560 miles. Driving it last night on the highway it random lost the speedo and at the same time dropped down a gear. I have no experience with automatic transmissions or where to even start. I pulled the code 14 which is the vss. Could loosening my vss reading have caused the trans to do this issue? Any information would be great! I need four wheel drive in the winter months and need to figure this out fast, or find another d21 to purchase.

Thank you very much!!!!!!!!!!