My REP with NCR is glitched i think, I was " accepted " by them. but then after doing " Dead Money " it somhow went to "dark hero" ???? and now, I have done at least 6 or 7 NCR quests, and my REP stays the same.... I don't get it??? Please help!!!

Are you wearing any NCR affiliated clothes? (Trooper, Ranger, Veteran armors)
Did you steal and or kill and NCR soldier detected?
Did you align with the Legion?
Did you complete a quest that opposed the NCR's goal?

Nope, came out of dead money, and BAM....

Your options:
1. Reload a earlier save.
2. Do some NCR quests to bring up your reputation. woops.
2 & 1/2. Wear NCR clothing for the rest of your Courier life (when around NCR, that is)
3. True to Caesar

If you're a dark hero you probally killed some then. What to do with regaining it and it isn't working, that is just unfortunate for you. Unless you load from after dead money then get a whole bunch of faction armor (NCR trooper armor, Great Khan Simple Outfit, Legion Veteran Outfit) and start switching them on and off, such as walk around in the armor for a minute, it should reset the faction popularity, or something like that.

wait...what??? how do i reset rep?

Are you on pc? If so, console commands will fix it in under 30 seconds. ^^

Sadly no,

There is a glitch that when you are switching armor around from factions Caesar's Legion and the NCR's reputation will reset to neutral. Don't know if it will work on everyone's though, but it does on mine.

Hmmm could you explain that in greater deatail?? im sorry,

Start by putting on a faction armor of your choice. Wear it for a minute.

Switch toa different faction armor. Wait a minute.

Switch to a different faction armor. Wait a minute. Do thsi until you Reputation resets to Neutral with Caesars Legion and the NCR.

Do nto wear NCR or CL armor while doing this.

Nope, i used Brotherhood and powder ganger armour... dident work.