My first working physics engine

/*
This is functional for the most part, but there are serious flaws. I can't seem to do collisions against the top of the player and bottom of a block and the player is prone to
falling through the floor if he jumps into corners in a specific way, such as this:
http://i.imgur.com/DhkPL.png
*/

//=========== Level.cs ============

//Go through each block
public static List<Block> CollisionsBottom()
        {
            List<Block> ret = new List<Block>();
            foreach (Block b in blocks)
            {
                if (b.IsCollision)
                {
//If b is a collision block, then make a rectangle from player to bottom of screen
                    if (b.Rect.Intersects(new Rectangle(Player.Rect.X, Player.Rect.Y, Player.Rect.Width, Util._STAGEHEIGHT)))
                    {
                        ret.Add(b);
                    }
                }
            }
            return ret;
        }
        public static List<Block> CollisionsRight()
        {
            List<Block> ret = new List<Block>();
            foreach (Block b in blocks)
            {
                if (b.IsCollision)
                {
                    if (b.Rect.Intersects(new Rectangle(Player.Rect.X, Player.Rect.Y, Util._STAGEWIDTH - Player.Rect.X, Player.Rect.Height)))
                    {
                        ret.Add(b);
                    }
                }

            }
            return ret;
        }
        public static List<Block> CollisionsLeft()
        {
            List<Block> ret = new List<Block>();
            foreach (Block b in blocks)
            {
                if (b.IsCollision)
                {
                    if (b.Rect.Intersects(new Rectangle(0, Player.Rect.Y, Player.Rect.X, Player.Rect.Height)))
                    {
                        ret.Add(b);
                    }
                }
            }
            return ret;
        }

//============== Player.cs ===============

private static void Physics()
        {
            if (Velocity.X > 0)
            {
                if (Math.Abs(DistToRight() - Rect.Width) > Velocity.X)
                {
                    if (Player.Rect.X < Util._STAGEWIDTH / 2 + 30)
                    {
                        Player.Rect.X += (int)Velocity.X;
                    }
                    else
                    {
                        MoveAll(Velocity);
                    }
                }
                else
                {
                    Velocity.X = 0;
                }
            }
            if (Velocity.X < 0)
            {
                if (Math.Abs(DistToLeft()) > Math.Abs(Velocity.X))
                {
                    if (Player.Rect.X > Util._STAGEWIDTH / 2 - 30)
                    {
                        Player.Rect.X += (int)Velocity.X;
                    }
                    else
                    {
                        MoveAll(Velocity);
                    }
                }
            }
//Only allow the player to move as long as distance to B is greater than his speed.
//Otherwise, player doesn't move.
            if (Math.Abs(DistToFloor()) > Player.Velocity.Y)
            {
                Velocity.Y += 1;
                Rect.Y += (int)Velocity.Y;
                onGround = false;
            }
            else
            {
                onGround = true;
                Velocity.Y = 0;
            }
        }
//Take the nearest block to the player that has collided with the rectangle and
//calculate the distance to it
        private static float DistToFloor()
        {
            Block b = Level.CollisionsBottom()[0];
                return Rect.Y + Rect.Height - b.Rect.Y;
        }
        private static float DistToRight()
        {

            if (Level.CollisionsRight().Count > 0)
            {
                Block b = Level.CollisionsRight()[0];
                return b.Rect.X - Rect.X;
            }
            return Velocity.X + 1;

        }
        private static float DistToLeft()
        {
            if (Level.CollisionsLeft().Count > 0)
            {
                Block b = Level.CollisionsLeft().Last();
                return Rect.X - b.Rect.X - b.Rect.Width;
            }
            return Math.Abs(Velocity.X) + 1;
        }