I suspect the glass cockpit has gone kaput. Has the backup ASI also gone?
S&L flight should not be too much of a problem, you can guestimate speed based upon common power settings.....egine sound / pitch / altimeter / known lever positions etc......
1) Request a PAR or SRA. If not available vectors to the FAF of the Loc approach and descend to correct altitude. At this point and altitude start descending down to minimums with radar guidance if available, or if not heading inbound course (which is protected with regards to terrain down to minimums). Come down quickly in this situation.
2) Pull the chute
Or pull my handheld GPS from the bag. Navigate to a the FAF of the loc approach and descend to required altitude, head on course using the handheld GPS, at the FAF start a descent down to minimums, or and make a perfect landing in time for tea and crumpets.
Do we not have any sort of nav kit in scenario 2? If not then you have to dead reckon your way to the FAF, whcih would be pretty tricky.