Have you ever asked yourself what prayer is? Prayer is simply talking with God - praising Him, confessing our sins, bringing our burdens and concerns to Him, and thanking Him for who He is and all He has done for us.
But prayer is also a privilege - and it is a privilege God has given us because He loves us! God wants us to pray! And He isn't offended if our efforts at prayer fall short of perfection - not at all. If you have children, do you remember when they first started to speak to you? Their words weren't eloquent or perfect - but that didn't matter to you, because you loved them and you were thrilled they were trying to talk with you.
The same is true with God. He is our loving Heavenly Father - and He delights in our prayers, no matter how simple or humble they may seem. The Bible says, "Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, present your requests to God" (Philippians 4:6). Remember that the Lord's Prayer begins with these words: "Our Father ..." (Matthew 6:9).
Written prayers may have their place; I have found them useful myself from time to time. But don't be afraid to speak to God in your own words also. God delights in the prayers of His people.