Doc told my man he cant have kids... but we want them

Drs have told my man he cant have kids due to being kicked in the nuts all the time, and a recent infection hes clean now tho but he has low sperm count. Ive seen people go on to have kids after they were told they couldnt, so i dont think its impossible for us to conceive, however it may be harder. Any advice on what we could do to boost his fertility or make conceiving easier?