Updating 5s to iOS 9.2 and 9.2.1 causes all apps to immediately crash and system instability

Updated 5s to ios 9.2 three weeks ago. Experienced all except 1 app crash consistently either immediately or within 2 seconds of loading. Checking for new software update gave error "unable to check for software update", email immediately crashes or attempts to load then crashes right before loading, new messages show on lock screen but do not appear once iPhone is unlocked, etc... Total app/system instability. Consistent for more than a week. Without changing anyone, one day everything performed normally for 8 hours or so, including checking for a new software update. Did not install new update at that time for fear of more/regression of incompatibility issues. After 8 hours all apps/system stability failed and returned to the previous day's status/ability MINUS the ability to check for a software update, 9.2.1 was still available so I downloaded it, no change. Phone is useless minus the one working app. Hard reset has been attempted 35+ times. software is currently up to date with 9.2.1