Investors & landlords

I bought 100 sh AOL back in 1994, for 743.00 which expanded to 800 sh when Time Warner merger. I have been reporting the various mergers, etc spin off's etc and paying taxes on the spin offs at 100%. Now I have the resulting 266 shares of ATT and cash of over 14,000 and have  no idea re cost basis since now . I have  no clue re cost basis. I  assume it is not paying taxes on the over 14,305. .I still have 32 sh of Comsat that was spun off. All the spin offs I paid 100% as gains. but I dont want to pay tax on the 14305. Anyone know what my cost basis is?