Someone thinks that he might have said some of the divorce words, but he isn't sure if he said these words or not. What is the solution?

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
According to the consensus of Muslim scholars doubt alone does not have any weight concerning divorce of one's wife. The Muslim jurists divide doubt in three categories:
1. The doubt which is considered null, (having no weight, as though they don't exist) according to the agreement of jurists.
2. The doubt which may have some weight or importance and regarded as legal according to the consensus of Muslim jurists.
3. Those doubts, which Muslim scholars differed concerning their rule, whether they may be acceptable or not, i.e., to be acted upon or not.
An example of the first kind of doubt is if a person doubts whether he divorced or not. This doubt is null (has no weight) according to the consensus of the Muslim scholars, because the compulsory condition for a valid divorce is one should pronounce the word of Talaq, or the words which indicate Talaq, intentionally and freely.
Allah knows best.