not going to solve the problem!!!!
I tried all that, reseting or forgetting the network will not solve this problem. people keep saying basic stuff that won't solve the problem. If they have the same problem, the Incorrect password Issue, they will know what the ones who have the problem are experiencing. U have in here two choices, restore using Itunes and start from scratch or if u are jailbroken, try pushfix tweak, and im sure it will help since i had the problem and now i have no issue.
I noticed that this problem happened as we keep installing new firmware for the router and we change the password frequently. This is a bug that is in ios. it really mind-blowing if u have this problem, u keep entering the right password and it always says INCORECT. by chance, the pushfix tweak helped me and after respring my phone connected using the password on WPA2 Personal encryption.