On Avodart for 7 years and lost erection and penis ejaculation. If I stop it for 6 months to see if both return, will it harm the prostate in any way?

No harm in trying. Yes you can stop Avodart safely. it works minimally and takes time, so a 6 month gap to regain your sexual function is well worth the effort. Good luck.
No, but try and see. Known to us, Avodart (dutasteride) is used to shrink the prostate by about 15-25% of its volume so to improve urine flow, but coming along with its collateral side effects like erectile dysfunction. To test how stopping its use may return sexual function, just stop it and see, but preferably under professional monitoring. More? To articles in http://formefirst.com/onBPH-LUTS-VoidingTrouble.html.