If a specific section is blocking your progress, you can lower the game difficulty at any time. Dropping down to or Medium grants you more instincts, weaker enemies, and checkpoints, allowing you to breeze through tough sections to unlock the rest of the campaign. Full Hitman: Absolution Mission List
Search community sites like Nexus Mods or dedicated Hitman fan forums for a "100% Save Game." hitman absolution all missions unlock link