Before taking any medications please check for diabetes. Diabetes is a common cause for erectile dysfunction and diabetes has to be treated. If your are not diabetic, you can take tablets such as Sildenafil and tadalafil. These drugs should be taken 3-4 hrs before intercourse ; usually they are very effective but they should not be taken if your are also taking nitrate medicine. In case if these medicines are not effective another drug- alprostadil can be injected into the muscles of the penis or drops of this medicine can be inserted into the meatus of the urethra. You have to remember that erectile dysfunction is a temporary phenomenon and in most cases it becomes alright even without treatment. So do not become anxious.