How to add momentum for this situation?

[Detonatress]

I'm using this code in step:

//Player Movement
hspeed = 5 * (keyboard_check(ord('D')) - keyboard_check(ord('A')))
vspeed = 5 * (keyboard_check(ord('S')) - keyboard_check(ord('W')))

//Collision
if !place_free(x+hspeed,y)
{
speed = -6
}

if !place_free(x,y+vspeed)
{
speed = -6
}

if !place_free(x+hspeed,y+vspeed)
{
speed = 0
}

I have tried what this video says,
https://www.youtube.com/watch?v=XzvDhpnRVtE

However the code is not doing anything, and the character stops as soon as I stop pressing the keys. Here is how I've tried to adapt it to my case:

// Momentum
acc=2
hspeed+=acc*(keyboard_check(ord('D')) - keyboard_check(ord('A')))
vspeed+=acc*(keyboard_check(ord('S')) - keyboard_check(ord('W')))
speed*=0.8

Can someone tell me what I'm doing wrong here, please?

[Detonatress]

How can I get a more accurate diagonal movement while using the hspeed and vspeed? It currently tends to go out of its path, and with this code (which is doing the momentum thing I needed) it seems all the more obvious that there is a bias towards the x or y axis.

hspeed += 6* (keyboard_check(ord('D')) - keyboard_check(ord('A')))
vspeed += 6* (keyboard_check(ord('S')) - keyboard_check(ord('W')))


friction = 0.2
if speed > 6
{
speed = 6
}