If the DP ports were working prior to cleaning the PC and now not working even after swapping out cables and monitor then it sounds as though the cleaning may have damaged the graphics card.
By cleaning do you mean simply blowing dust out of the PC using compressed air? Was any hardware removed during the cleaning process? Did you disassemble the card for a re-paste as part of the cleaning?
Ryzen R7 5700X | B550 Gaming X | 2x16GB G.Skill 3600 | Radeon RX 7900XT
Ryzen R7 5700G | B550 Gaming X | 2x8GB G.Skill 4000 | Radeon Vega 8 IGP
Ryzen R5 5600 | B550 Gaming Edge | 4x8GB G.Skill 3600 | Radeon RX 6800XT