I handed my bitcointalk account to my friend few years ago and he started doing paid shit posting. Now I asked him to provide me the account login and when I checked that its simple got down voted.
Is there anyway to fix my account reputation?
Well, then you made a big mistake, (but this is if, like other members have said, you are not the friend you referring to).
I can decide to misuse my account and come back tomorrow to tell people that a friend I lended my account to misused it, please forgive me and remove the negative trust people... It doesn't work that way bro, if it does, then there will be alot of scammers in this forum.
Imagine a friend pushed you to go killing some one, and after killing the person, God calls you out for killing, and you say it's a friend who pushed you to do it, does that stop God from punishing you...No.
In the Bible, Eve convinced Adam to eat the forbidden fruit, and when God asked adam, "why did you eat it?" Adam answered, "the woman you (God) gave me made me eat" and God said "because you listened to your wife, the ground is cursed for your sake"
This is why privacy is highly valued, be careful who you share your private stuff with, cus when you hand over your private stuff to a person, you automatically give that person access to you.. Whatever they do with that which you gave them comes back to hurt you.