I had to loosen my tension on the loom when I realized what happened, and started to insert sticks and gently work them around the beam to get back to the start. It's better if you don't forget, since it isn't a good idea to loosen the tension too much. You can see one of the sticks as I started to insert it. Moulding used to attach screening to wooden doors works well if it is given a light sanding. Big box home improvement stores or lumber yards stock it.
After the back beam is covered once, I use heavy paper or window shades to keep the rest of the layers separate. It is ok to use just sticks, if you are putting a short warp on, but don't stack them, since they could slip. It isn't very economical for a long warp, since sticks are more expensive than heavy paper, and they will fill the beam more quickly than paper.
The separation of layers is very important to prevent individual threads from sinking into previous layers. If that happens, the warp threads are no longer the same length, and will cause the warp tension to be uneven.
My warps are wound under tension. A trapeze works well when winding a warp without help. That is another subject and has been discussed in previous posts.
Once the cloth is smooth on the front beam, there isn't any reason to separate the layers.