Bonehead electrical outlet mistake repair question

[hynostroza]

We moved into a new house and in the master bedroom there is a light switch on the left side entrance of the room and also another switch on the opposite side of the room that controls an outlet power. I went out and bought all new outlets for all the room, seeing the ones that were here were very outdated and just seemed rather cruddy. Opening up the outlet (which the light switches control) I noticed the copper wires were all brittle and just full of gunk. Anyways here's my bonehead mistake there were a group of wires bundled together with electrical tape that was coming a part already among those wires were four black wires and one white wire which seemed liked there is a black stripe on it all twisted into one and had electrical tape around it. Well I thought I put back the same wires that were off the outlet but seeing now 4 black wires AND the original black wire from the outlet there were 5 and so after putting them back and seeing if the outlet works which it does, but if you switch off the light switch in the master bedroom the other rooms light go off. So my question for this repair is that, what are those 4 wires and white wire connected together for? and is it going to be possible to be able to hook up an outlet in the master bedroom without the light switches turning off the outlet? thank you

[HayZee518]

wiring problem

the white wire with the black stripe is a feed to one of the switches, or a return from one of the switches. Being bundled together with four other black wires tells me it a feeder for some other device.
when you say there's a lot of "gunk" inside the box, do you mean on the wires? my reason for asking this, is, the wires may be copper clad aluminum wire and this "gunk" is a necessary anti-oxidant.
answer me this question, then we'll proceed to further your problem.

[hynostroza]

Thank you for your quick response Hayzee517. The gunk was in fact electrical tape that i'm thinking might of been sorta melted down over years, it wasn't shrink tubing because I use that all the time and it wasn't that. I just want to correct this issue.

[HayZee518]

bedroom lighting

ok, two switches in the same room means a three way light circuit. the lights can come on or off from two locations. also, one or two receptacles are "split wired" meaning one half is switched and the other should always be hot. two of your outlet boxes will have a red, black and a white plus a bare ground. the rest will have only a black, white and bare ground. in the first wall switchbox a hot wire will be connected to the odd colored screw. then a three wire will connect to the other switchbox [if the wiring was done according to code] a red and black of the three wire connects to the two brass screws of one three way switch, the white is spliced with the line neutral. at the remote box, the black and red of the three wire connects to the two brass screws, and the load is taken off the odd colored screw. this may be connected to a red wire that goes between two outlets and the switch. the whites are not switched but are connected to the white neutral.