Both Cialis and Viagra are options, but really don’t work most of the time. You can try 100 mg of Viagra. There’s even a generic type what you can get in 20 mg pills.

A penis pump would get you an erection. You have to put a tight ring around the base of the penis to keep it erect. It may not get as hard as you’d like. It’s a good way to at least train your penis to get an erection and maybe then the Cialis or Viagra will work. I was given one right after I was finished with surgery, it did work but not real comfortable to use.

The only real successful technique is Trimix or a combination of one or two of the drugs used in Trimix. You have to go to your urologist to learn how to use it. The needle is very thin and small, easy to do.

1) Other than injections and penile implants, the treatments include the drugs called PDE5 inhibitors, which include tadalafil and sildenfil, (brand names cialis and viagra) as well as vacuum erection devices [VED].
2) tadalafil has a longer decay curve than other PED5 inhibitors, and a low dose would be 5mg.
3) the penis contains what they call "smooth muscle tissue" or "cavernous smooth muscle cells" or the "corpus cavernosa." [There are two. Each is a corpus cavernosum.] Like other muscles, they can atrophy with disuse. People with normal erectile function have night time erections (during sleep) that keep these muscles from atrophy. After trauma and/or nerve damage from surgery, ablation [like cryo], or radiation, these can stop. The longer these muscles go without stimulation the more they may atrophy, making recovery of function more difficult. VED therapy*, PED5 inhibitors, and injections all [may] provide engorgement which exercises this smooth muscle tissue--using it so as not to lose the ability to use it through prolonged atrophy.
*VED therapy involves using successive cycles of vacuum around the part of the penis that protrudes from the body to produce engorgement of the corpus cavernosa. This exercises the muscles without regard to whether intimacy and sexual stimulation are involved or follow.
4) Physical stimulation may be more necessary for erectile function after trauma and/or nerve damage than previously, when sexualized thoughts and emotion might have been enough on their own. Hands are one of the most flexible and available instruments for such stimulation.

Hi @syoozi, here is a link to a video of a very frank discussion, "Restoring Sexual Function After Prostate Cancer Treatment", which I found very informative. Features Dr. Tobias Kohler, an expert "men's health" urologist at the Mayo Clinic in Rochester, MN. Hope this is helpful to you and your partner.

I forgot to mention one specific procedure, and that is to install an implant in the penis.

I attended a webinar last week where they talked about different procedures for resolving erection problems. At the end the doctor talked about doing implants. He said they were very successful and almost everyone was really pleased with the results. An implant guarantees a good solid erection. It is a long term solution.