Sola Scriptura, or Scripture Alone, is the first pillar in the 5 Solas of the Reformation. It is this pillar that the rest of them rest upon. Why? Because this means that Scripture is the final authority on all matters.
Luther had serious problem with a man (the pope, priest, cardinal, etc...) being the final authority on things. Therefore, he was abundantly clear that the ultimate authority is the Word of God.
We are fortunate to have the Bible in our language. For years a lot of people were not able to read the Bible, because it was in a different language. However, we don't have that problem. It was the desire of the reformers to have the Scriptures in the language of the people.
This fact enabled individuals to read the Bible themselves and interpret it. Before this point, most solely relied on the teachings of the Roman Catholic Church.
Why can we still hold firmly to Sola Scriptura? First, because the Bible was authored by God. The Holy Spirit inspired the writers of Scripture to write what they wrote. The Bible says it was "God breathed." That is to say the Word came from a singular source, God.
Secondly, the Scriptures are completely accurate. God is perfect therefore, His Word is perfect. You and I can completely trust the Word. In a world that is full of lies, it is fabulous to know there is a Word we can rest out lives upon.
Finally, the Scriptures are completely sufficient. We can believe Sola Scriptura because the Scriptures are all we need. As a believer, I'm not to look to any other source for guidance. I hear preachers erroneously say something like, "I have a word from God." What they are saying is that God has given them a revelation He has not given anyone else. This is heresy. God has given us the complete revelation in Scripture and that's all that's needed.
It is my hope that you are resting your life on the truths of God's Word. They will never fail you.