One implant failed. How soon can I attempt to replace it?

This varies in every case and area of the mouth, but I would say the average wait time is 3-4 months before attempting another implant.  The use of a 3D CT scan is very beneficial in determining if adequate bone is present to attempt another dental implant. Good luck.  

usually a bone graft procedure is done once the failed implant is removed ( depending on amount of bone destruction as a result of infection around the failing implant) Depending of the amount of bone regeneration needed, a wait time of 4-6 months is needed before another implant is placed pending adequate bone regeneration. If Bone graft is not done at the time of removal of this failed implant, about 2-3 months of healing is neededusually a CBCT scan is done to evaluate the available bone and decide if a new implant could be placed.  If adequate bone is not present, the bone will need to be regenerated. 

minimum wait time after implant failure is 3 months, ideal wait time is 6 months. if socket is filled with bone graft, it will take little longer time.

Depends on the situation.  If adequate bone is still present in the area, it could be done relatively soon.  If grafting is required which is often the case, usually 3-4 months minimally would be required for adequate healing before attempting another implant in the area.

If you are looking to put another implant in the same location you will usually have to wait 3 months for bone healing.  Then if the site is good an implant can be placed

The question of replacement is a bit more complicated and requires a bit more information. If the implant failed immediately after placement, then generally at 6 to an 8 week period is enough  I will waiting time to go back and replace it. The question becomes more complicated if the failure of the original implant is after years of use and there was lots of bone loss. In that case,  bone regeneration may be necessary and the waiting period might be much longer. Either way, this question should be posed to the surgeon placing the implant. Best of luck,

There are 4 types of bone , depends on the area where you lost that implant , and also the type of bone quality you have , if you are young and healthy , 3 months , if not at least 6 .the cause of failing implant is important, overload? Wrong higyene?.this tells much about it.