[admin@MikroTik] > /interface wireless print
Flags: X - disabled, R - running
0 R name="wlan1" mtu=1500 mac-address=D4:CA:6D:32:01:3F arp=enabled interface-type=Atheros AR9300 mode=station ssid="MikroTik" frequency=2412 band=2ghz-b/g channel-width=20mhz scan-list=default wireless-protocol=any vlan-mode=no-tag vlan-id=1 wds-mode=disabled
wds-default-bridge=none wds-ignore-ssid=no bridge-mode=enabled default-authentication=yes default-forwarding=yes default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=no security-profile=default compression=no

[admin@MikroTik] > /system resource print
uptime: 41m18s
version: 6.28
build-time: Apr/15/2015 15:18:31
free-memory: 96.0MiB
total-memory: 128.0MiB
cpu: MIPS 74Kc V4.12
cpu-count: 1
cpu-frequency: 600MHz
cpu-load: 5%
free-hdd-space: 36.6MiB
total-hdd-space: 128.0MiB
write-sect-since-reboot: 1250
write-sect-total: 5261408
bad-blocks: 0.1%
architecture-name: mipsbe
board-name: RB2011UAS-2HnD
platform: MikroTik

You probably need to install some wireless package and enable the wlan manually.

[admin@MikroTik] > /system package print
Flags: X - disabled
# NAME VERSION SCHEDULED
0 lte 6.36
1 system 6.28
2 advanced-tools 6.28
3 calea 6.28
4 dhcp 6.28
5 gps 6.28
6 hotspot 6.28
7 ipv6 6.28
8 lcd 6.28
9 mpls 6.28
10 multicast 6.28
11 ntp 6.28
12 openflow 6.28
13 ppp 6.28
14 routing 6.28
15 security 6.28
16 ups 6.28
17 user-manager 6.28
18 wireless-fp 6.28
19 X wireless 6.28

And you don't see any wireless interface? Have you updated the firmware too?

I have seen that on 6.37, on first time upgrade, the wireless package is disabled and the configuration is lost.
If you have a configuration backup file on the device?
If yes, enable the wireless package, restore the backup it and reboot. This should fix it.

http://forum.mikrotik.com/viewtopic.php ... 25#p549613

[admin@MikroTik] > /interface wireless scan
number: 0
Flags: A - active, P - privacy, R - routeros-network, N - nstreme, T - tdma, W - wds, B - bridge
ADDRESS SSID CHANNEL SIG NF SNR RADIO-NAME
AP BC:AE:C5:EC:19:9B ASUS-Den2G 2427/20-Ce/gn -80 -95 15
AP DC:02:8E:B3:6A:37 MGTS_GPON_6E27 2437/20/gn -59 -97 38
AP DC:02:8E:B1:BA:1B mgts100 2437/20/gn -68 -97 29
AP CC:7B:35:D1:8C:30 MGTS_GPON_244 2437/20/gn -87 -97 10
A 38:2C:4A:98:8A:13 MuHyS-Free 2437/20/gn -90 -97 7