Yes, the loss of curve can be cured. Will "the spine be as normal as earlier"? Maybe, maybe not. A herniated disc will lose some height but doesn't mean it has to cause permanent pain and dysfunction.
Ligaments hold the bones together. When ligaments (discs) stretch or tear, they cannot hold the bones in the correct alignment. The torn fibers can heal.
1) Do a Google search for "Static extension on elbows"
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2) Do a Google search for "Static back Position". Look at the link from "Theposturedude". I put two foam balls the size of tenis balls under my lower back / hips to put an arch in my lower back.
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3) Do a google search for "Seated hip abductor press" but use a Yoga strap just above your knees instead.
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4) Get a lumbar support to help keep your back arched when sitting. My favorite is "The Original McKenzie Airback TM Inflatable Roll #706"