There has to be some type of probate done on your father's will to pass title to the property before it can be sold.
When someone passes away there is instantly a legal entity created called "the Estate of ...". That legal entity actually owns all of the property the deceased owned. A probate is done to pass title to the property.
There are several ways to do a probate, a full probate through the court or an informal type of probate such as an Affidavit of Heirship
. The kind that you need depends on all of the facts but something has to be done or else a title insurance company won't insure title to the property and therefore it can't be financed or sold.
However, if a piece of property is owned by more than one person then that person can always file a Suit to Partition Property and the court will either divide it, which can't really be done in the case of a house, or 1) allow one or more of the heirs to buy the others out of their interests in the property or 2) order the property to be sold and the money divided.
I can't advise you as to spending your money on fixing up the house, that goes beyond what the site allows us to do, and I can't tell you how long the entire process will take. What I can tell you is that if a joint owner of the property wants their share sold then it will be sold, either to the other owners or someone else.