C# SQLITE Unlock database

i update my code with this code:

<code>sql = "UPDATE tableelements SET myelement= '" + textBox1.Text + "' WHERE id = '" + TextBox4 + "'";
command = new SQLiteCommand(sql, connectiondb);
command.ExecuteNonQuery();</code>

when i executed he's work perfectely without any problem but when i try it again i get an error who say:

SQLite.SQLiteEXception(0x80004005): Database is locked

:( i dont know what ill do :(

help please